The result for far.

Shader "Unlit/ChromaDepthEdge" {

Properties
{
    _MainTex ("Texture", 2D) = "white" {}
    _Ramp ("Texture", 2D) = "white" {}
    _Threshold("Threshold", Float) = 0.1
}
SubShader
{
  Pass
  {
      ZTest Always Cull Off ZWrite Off
      CGPROGRAM
      #pragma vertex vert
      #pragma fragment frag
      #pragma target 3.0
      #include "UnityCG.cginc"
        
      struct appdata
      {
          float4 vertex : POSITION;
      };
  
      sampler2D _MainTex;
      sampler2D _Ramp;
      // Request camera depth buffer as a texture.
      // Incurs extra cost in forward rendering, "just there" in deferred.
      sampler2D _CameraDepthTexture;
      float4 _MainTex_TexelSize;
     
            
      float4x4 _InverseViewMatrix;
      
      float _Threshold;
        
      void vert (
          float4 vertex : POSITION,
          out float4 outpos : SV_POSITION)
      {
          outpos = UnityObjectToClipPos(vertex);
      }
  
      fixed4 frag (UNITY_VPOS_TYPE screenPos : VPOS) : SV_Target
      {
          // Convert pixel coordinates into screen UVs.
          float2 uv = screenPos.xy * (_ScreenParams.zw - 1.0f);
          
          //uv.y = (uv.y *-1) + 1;
          // Depending on setup/platform, you may need to invert uv.y
          // Sample depth buffer, linearized into the 0...1 range.
          float depth = Linear01Depth(
                UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv)));   
       
          float2 uvDist = 3 * _MainTex_TexelSize.xy;
          
          float depthUp =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(0, 1))));   
          float depthDown =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(0, -1))));   
          float depthLeft =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(-1, 0))));   
          float depthRight =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(1, 0))));   

          float mean = ((depthUp - depth) + (depthDown - depth) + (depthLeft - depth) + (depthRight - depth)) / 4;
                                                            
          // Compressing the range, so we get more colour 
          // variation close to the camera.
          depth = saturate(2.0f * depth);
          depth = 1.0f - depth;
          depth *= depth;             
          depth = 1.0f - depth;     
          //return depth;
         
            
          // Use depth value as a lookup into a colour
          // ramp texture of your choosing. 
          fixed4 colour = tex2D(_Ramp, depth * 6 * _Time.y * 4);
           
          return lerp(colour, colour * 6, mean > _Threshold);
      }
      ENDCG
  }

}

}

The result for far. 

Shader "Unlit/ChromaDepthEdge"
{

    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Ramp ("Texture", 2D) = "white" {}
        _Threshold("Threshold", Float) = 0.1
    }
    SubShader
    {
      Pass
      {
          ZTest Always Cull Off ZWrite Off
          CGPROGRAM
          #pragma vertex vert
          #pragma fragment frag
          #pragma target 3.0
          #include "UnityCG.cginc"
            
          struct appdata
          {
              float4 vertex : POSITION;
          };
      
          sampler2D _MainTex;
          sampler2D _Ramp;
          // Request camera depth buffer as a texture.
          // Incurs extra cost in forward rendering, "just there" in deferred.
          sampler2D _CameraDepthTexture;
          float4 _MainTex_TexelSize;
         
                
          float4x4 _InverseViewMatrix;
          
          float _Threshold;
            
          void vert (
              float4 vertex : POSITION,
              out float4 outpos : SV_POSITION)
          {
              outpos = UnityObjectToClipPos(vertex);
          }
      
          fixed4 frag (UNITY_VPOS_TYPE screenPos : VPOS) : SV_Target
          {
              // Convert pixel coordinates into screen UVs.
              float2 uv = screenPos.xy * (_ScreenParams.zw - 1.0f);
              
              //uv.y = (uv.y *-1) + 1;
              // Depending on setup/platform, you may need to invert uv.y
              // Sample depth buffer, linearized into the 0...1 range.
              float depth = Linear01Depth(
                    UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv)));   
           
              float2 uvDist = 3 * _MainTex_TexelSize.xy;
              
              float depthUp =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(0, 1))));   
              float depthDown =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(0, -1))));   
              float depthLeft =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(-1, 0))));   
              float depthRight =  Linear01Depth(UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv + uvDist * float2(1, 0))));   

              float mean = ((depthUp - depth) + (depthDown - depth) + (depthLeft - depth) + (depthRight - depth)) / 4;
                                                                
              // Compressing the range, so we get more colour 
              // variation close to the camera.
              depth = saturate(2.0f * depth);
              depth = 1.0f - depth;
              depth *= depth;             
              depth = 1.0f - depth;     
              //return depth;
             
                
              // Use depth value as a lookup into a colour
              // ramp texture of your choosing. 
              fixed4 colour = tex2D(_Ramp, depth * 6 * _Time.y * 4);
               
              return lerp(colour, colour * 6, mean > _Threshold);
          }
          ENDCG
      }
  
    }
}

I'm trying to reproduce a post-effect with unity seen the answer here.

I'm trying to reproduce a post-effect with unity seen in the answer here.