Unity editor script converts Unity UI Text to TMP TextMeshPro text - tested in 2022.3.33f1 for VisionOS Polyspatial proj - with font mod https://forum.unity.com/threads/replacing-text-with-textmesh-pro.515594/#post-8339880

TextToTextMeshPro.cs

using UnityEngine;
using UnityEditor;
using UnityEngine.UI;
using TMPro;

public class TextToTextMeshPro : Editor
{
    public class TextMeshProSettings
    {
        public bool Enabled;
        public FontStyles FontStyle;
        public float FontSize;
        public float FontSizeMin;
        public float FontSizeMax;
        public float LineSpacing;
        public bool EnableRichText;
        public bool EnableAutoSizing;
        public TextAlignmentOptions TextAlignmentOptions;
        public bool WrappingEnabled;
        public TextOverflowModes TextOverflowModes;
        public string Text;
        public Color Color;
        public bool RayCastTarget;
        public TMP_FontAsset Font;
    }

    static private bool recursive = false;
    static private bool applyOnDisabled = false;
    static private bool removeEffectComponents = false;

    [MenuItem("Tools/Text To TextMeshPro", false, 4000)]
    static void DoIt()
    {
        if (TMPro.TMP_Settings.defaultFontAsset == null)
        {
            EditorUtility.DisplayDialog("ERROR!", "Assign a default font asset in project settings!", "OK", "");
            return;
        }

        recursive = EditorUtility.DisplayDialog("Text To TextMeshPro", "Process all the children of the selected objects recursively?", "Yes", "No");
        if (recursive) applyOnDisabled = EditorUtility.DisplayDialog("Text To TextMeshPro", "Process disabled objects too?", "Yes", "No");

        removeEffectComponents = EditorUtility.DisplayDialog("Text To TextMeshPro", "Remove obsolete component effects Shadow and Outline?\n\nThis components have no effect on TextMeshPro and can be safely removed.\nTo apply shadows and outlines on TextMeshPro components, use different materials instead.", "Yes", "No");

        foreach (GameObject gameObject in Selection.gameObjects)
        {
            if (recursive)
            {
                var childs = gameObject.GetComponentsInChildren<Transform>(applyOnDisabled);
                foreach (var ch in childs)
                    ConvertTextToTextMeshPro(ch.gameObject);
            }
            else
                ConvertTextToTextMeshPro(gameObject);
        }
    }

    static void ConvertTextToTextMeshPro(GameObject target)
    {
        if (removeEffectComponents)
        {
            var sha = target.GetComponents<UnityEngine.UI.Shadow>();
            foreach (var cmp in sha) Undo.DestroyObjectImmediate(cmp);
            var outl = target.GetComponents<UnityEngine.UI.Outline>();
            foreach (var cmp in outl) Undo.DestroyObjectImmediate(cmp);
        }

        Text uiText = target.GetComponent<Text>();
        if (uiText == null) return;


        TextMeshProSettings settings = GetTextMeshProSettings(uiText);

        Undo.RecordObject(target, "Text To TextMeshPro");
        Undo.DestroyObjectImmediate(uiText);

        TextMeshProUGUI tmp = target.AddComponent<TextMeshProUGUI>();
        tmp.enabled = settings.Enabled;
        tmp.fontStyle = settings.FontStyle;
        tmp.fontSize = settings.FontSize;
        tmp.fontSizeMin = settings.FontSizeMin;
        tmp.fontSizeMax = settings.FontSizeMax;
        tmp.lineSpacing = settings.LineSpacing;
        tmp.richText = settings.EnableRichText;
        tmp.enableAutoSizing = settings.EnableAutoSizing;
        tmp.alignment = settings.TextAlignmentOptions;
        tmp.enableWordWrapping = settings.WrappingEnabled;
        tmp.overflowMode = settings.TextOverflowModes;
        tmp.text = settings.Text;
        tmp.color = settings.Color;
        tmp.raycastTarget = settings.RayCastTarget;
        tmp.font = settings.Font;
        Debug.Log(target.name + " converted to TextMeshProUGUI");
    }

    static TextMeshProSettings GetTextMeshProSettings(Text uiText)
    {
        if (uiText == null)
        {
            EditorUtility.DisplayDialog("ERROR!", "You must select a Unity UI Text Object to convert.", "OK", "");
            return null;
        }
        string fontName = uiText.font.name;
       // Debug.Log("fontName " + fontName+".");
        var results = AssetDatabase.FindAssets(fontName + " t:TMP_FontAsset", null);
      // Debug.Log("results " + results.Length);
        if (results==null || results.Length < 1)
        {
            results = AssetDatabase.FindAssets(fontName + " SDF t:TMP_FontAsset", null);
        }
       // Debug.Log("results " + results.Length + " " + AssetDatabase.GUIDToAssetPath(results[0]));

        return new TextMeshProSettings
        {
            Enabled = uiText.enabled,
            FontStyle = FontStyleToFontStyles(uiText.fontStyle),
            FontSize = uiText.fontSize,
            FontSizeMin = uiText.resizeTextMinSize,
            FontSizeMax = uiText.resizeTextMaxSize,
            LineSpacing = uiText.lineSpacing,
            EnableRichText = uiText.supportRichText,
            EnableAutoSizing = uiText.resizeTextForBestFit,
            TextAlignmentOptions = TextAnchorToTextAlignmentOptions(uiText.alignment),
            WrappingEnabled = HorizontalWrapModeToBool(uiText.horizontalOverflow),
            TextOverflowModes = VerticalWrapModeToTextOverflowModes(uiText.verticalOverflow),
            Text = uiText.text,
            Color = uiText.color,
            RayCastTarget = uiText.raycastTarget,
            Font = (TMP_FontAsset)AssetDatabase.LoadAssetAtPath(AssetDatabase.GUIDToAssetPath(results[0]), typeof(TMP_FontAsset))

        };
    }

    static bool HorizontalWrapModeToBool(HorizontalWrapMode overflow)
    {
        return overflow == HorizontalWrapMode.Wrap;
    }

    static TextOverflowModes VerticalWrapModeToTextOverflowModes(VerticalWrapMode verticalOverflow)
    {
        return verticalOverflow == VerticalWrapMode.Truncate ? TextOverflowModes.Truncate : TextOverflowModes.Overflow;
    }

    static FontStyles FontStyleToFontStyles(FontStyle fontStyle)
    {
        switch (fontStyle)
        {
            case FontStyle.Normal:
                return FontStyles.Normal;

            case FontStyle.Bold:
                return FontStyles.Bold;

            case FontStyle.Italic:
                return FontStyles.Italic;

            case FontStyle.BoldAndItalic:
                return FontStyles.Bold | FontStyles.Italic;
        }

        Debug.LogWarning("Unhandled font style " + fontStyle);
        return FontStyles.Normal;
    }

    static TextAlignmentOptions TextAnchorToTextAlignmentOptions(TextAnchor textAnchor)
    {
        switch (textAnchor)
        {
            case TextAnchor.UpperLeft:
                return TextAlignmentOptions.TopLeft;

            case TextAnchor.UpperCenter:
                return TextAlignmentOptions.Top;

            case TextAnchor.UpperRight:
                return TextAlignmentOptions.TopRight;

            case TextAnchor.MiddleLeft:
                return TextAlignmentOptions.Left;

            case TextAnchor.MiddleCenter:
                return TextAlignmentOptions.Center;

            case TextAnchor.MiddleRight:
                return TextAlignmentOptions.Right;

            case TextAnchor.LowerLeft:
                return TextAlignmentOptions.BottomLeft;

            case TextAnchor.LowerCenter:
                return TextAlignmentOptions.Bottom;

            case TextAnchor.LowerRight:
                return TextAlignmentOptions.BottomRight;
        }

        Debug.LogWarning("Unhandled text anchor " + textAnchor);
        return TextAlignmentOptions.TopLeft;
    }
}