スクリプトからマテリアルの色（Properties）を変更する

Sample.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace Sample {
    public class MatColorController : MonoBehaviour
    {
        public Material mat;
        [Range(0,1)] public float opacity = 1.0f;
        [Range(0,5)] public float coff;

        private int id;

        void Start()
        {
            id = Shader.PropertyToID("_Color");
        }

        void Update()
        {
        float r = Mathf.Sin(Time.time * coff);
        float g = Mathf.Cos(Time.time * coff);

        // -1 ~ 1 => 0 ~ 1 にRemap
         r = r.Remap(-1,1,0,1);
         g = g.Remap(-1,1,0,1);

        Color Cd = new Color(r, g, 1.0f, opacity);

        mat.SetColor("_Color", Cd);
        }
    }

    public static class MathExtensiton {
        public static float Remap(this float value, float from1, float to1, float from2, float to2)
        {
            return (value - from1) / (to1 - from1) * (to2 - from2) + from2;
        }
    }
}

Sample.shader

Shader "Unlit/Sample Shader"
{
    Properties
    {
        _Color("Color", Color) = (1, 1, 1, 1)
    }
    SubShader
    {
        Tags {
            "RenderType"="Transparent"
            "Queue" = "Transparent"
         }
        LOD 100

        Blend SrcAlpha OneMinusSrcAlpha

        Pass
        {

            // ----------中略----------

            fixed4 _Color;

            // ----------中略----------

            fixed4 frag (v2f i) : SV_Target
            {
                return _Color;
            }
            ENDCG
        }
    }
}