Unity component to change a visual effect's play rate.

VisualEffectPlayRate.cs

using UnityEngine;
using UnityEngine.VFX;

[ExecuteInEditMode]
[RequireComponent(typeof(VisualEffect))]
public class VisualEffectPlayRate : MonoBehaviour
{
    [SerializeField, Range(0, 10)] float playRate = 1f;

    VisualEffect vfx;

    void OnValidate()
    {
        vfx = GetComponent<VisualEffect>();
    }

    void Update()
    {
        vfx.playRate = playRate;
    }
}