Hi @Irfan Mohammed ,
Thanks for your question, you're on the right track!
Step 1: The first step would be to migrate your classic resources to ARM resources if you follow the doc you pointed out here you should be able to do that.
Step 2: After you follow the steps in that doc to migrate your resources to new ARM resources you can easily migrate your resource group to a new subscription using this doc here. Personally I'd advise using the Azure Portal for this as if you have only one RG its the easiest.
If this helps you answer your question please mark it as accepted so other community members can find it. Thanks!