apple tv not showing app & I can't download from app store

inherited the Apple TV hardware

It is recommended to reset the device for a new owner, to get rid of all the previous user’s settings. Then you don’t have to search for all instances where the old account was used.

If I try to download an app from the app store and I already have it; the app's "update" option requires me to log in with the prior owner's info. If I delete the app, then re-download, I can log in without problem.

App Store apps stay linked to the account that was used to install them initially. That is why deleting and re-downloading would apply the new account to the fresh app.

My issue is that the Paramount+ app does not show in my apps but when I try to download it, it shows "update" and I need to login to the previous owner's account.

Then I believe this app is still installed on the device somewhere. Search the Home Screen and the folders.