How to generate hash of a file using certificate information and sha-256

Question

Is it possible to generate hash of a file using certificate information? I have certificate details like this

    "details": {
        "certificate": "XIIHBTCCBO2gAwIBAgIQGuE3Q0ztnKRiYRN.....",
        "public_key": "XIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQE...."
    },

Using this information I need to create a digestvalue. Assuming the digest value is hash of a file created using the above certificate.

I am using below code to generate hash, but not able to figure out how to use certificate as well.

    public static string SHA256CheckSum(string filePath)
    {
        using (SHA256 SHA256 = SHA256Managed.Create())
        {
            using (FileStream fileStream = File.OpenRead(filePath))
                return Convert.ToBase64String(SHA256.ComputeHash(fileStream));
        }
    }