How do I add 'channels' to my Apple TV 4k Main Menu?

Hello,

I've been searching on how I can add channels I subscribe to through the Apple TV+ app on my Apple TV 4K box to the main menu on my Apple TV 4k (did I say Apple TV enough in that sentence?)

I just subscribed to CBS All Access/Showtime through Apple TV+ but it seems I can only access those by going into the Apple TV+ app when I would much rather add the CBS All-Access and Showtime channels to my main menu and access them there.

Is there a way to do this or do I always have to go through the Apple TV+ app first then click on those channels in order to access them?

Thanks for the help.