public static class EnvHelper
{
    public static string ENV_VAR_A => GetEnvVar();
    public static string ENV_VAR_B => GetEnvVar();
    public static string ENV_VAR_C => GetEnvVar();
    
    private static string GetEnvVar([CallerMemberName] string name = null) 
        => Environment.GetEnvironmentVariable(name);
}

/* content .env file
ENV_VAR_A=value A
ENV_VAR_B=value B
ENV_VAR_C=value C
*/