@Christopher Hoard That nearly worked. What I am trying to achieve is a link from a News Custom tab I created to the Posts tab on the same channel. When I try your solution in the Teams App I get the following.
I don't think there is a means to switch within the app to the posts tab as there is no link to tab exposed. You could, as a workaround try link to a post in the post channel. What I mean here is click the ellipsis (...) on a post, say a welcome message, and try that but it may do the same behaviour as the link to channel