@Sahu, Divya While it may be possible to do things this way, it is more work than it needs to be, kind of like if you needed some oil for your car you made a deal with the parts manufacturer instead of just going to the local hardware store.
The release pipeline is generally for taking one Factory / Workspace and copying all its contents to another Factory / Workspace.
The easier way to add a linked service is just go go use the visual authoring tool / portal. This way the Linked Service gets written into your repo properly.
By directly using ARM template, you would bypass your repo, and cause the repository and Factory/Workspace to become out of sync.
Does this make sense?