Works with stencil buffer and scripts to create graphic drop shadow on certain objects.

DropShadowShader

Shader "Unlit/dropShadowShader"
{
    Properties
    {
        _ShadowColor ("Shadow Color", Color) = (0, 0, 0, 1)
        _Range ("Range", Range(0, 1)) = 1
        _DropOffset ("Offset", Vector) = (0.03, -0.01, -0.02)
        _AlphaCutoff ("Alpha Cutoff", 2D) = "white" {}
        //_stencilRef("stencil reference", Int) = 1
    }
    
    SubShader
    {
        Tags { "RenderType"="Opaque" "Queue"="Geometry+1"}
        
        
        LOD 100

        Pass
        {
            Cull Off
            AlphaToMask On 
            //ZTest Off
            //ZWrite Off
            Offset 1, -1
     
            Stencil
              {
                    Ref 2
                    Comp notequal
               }
        
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            float4 _ShadowColor;
            float3  _DropOffset;
            float _Range;
            sampler2D _AlphaCutoff;

            v2f vert (appdata v)
            {
                v2f o;

                float3 viewSpacePos = UnityObjectToViewPos(v.vertex.xyz);
                o.vertex = mul(UNITY_MATRIX_P, float4(viewSpacePos + _Range * _DropOffset, 1.0f));

                o.uv = v.uv;
                
                /*float4 worldSpacePos = mul(unity_ObjectToWorld, v.vertex);
                float3 viewDir = normalize(UnityWorldSpaceViewDir(worldSpacePos));
                o.vertex = mul(UNITY_MATRIX_VP, worldSpacePos + (float4(viewDir, 0.0)));*/
                
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                float alpha = tex2D(_AlphaCutoff, i.uv).a;
                float4 color = _ShadowColor * (1, 1, 1, alpha);
                return color;
            }
            ENDCG
        }
    }
}