Ideally you should have done this when transitioning --> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support The iPhone has a new "owner" viz. a different account being used with it.
There are several likely places where you can use a different Apple ID:
1. In Mail if you want to use a different or more than one iCloud or other mail provider account, go to: Settings -> mail -> accounts -> add account -> iCloud
2. Messages and Facetime. Sign into a different Apple ID for these services in Settings. Note this has to be the same ID for both. Go to Settings > Messages > Send & Receive, and make sure both your telephone number and Apple ID are input there and both show a checkmark. If you need more help, check this link: Add or remove your phone number in Messages or FaceTime - Apple Support .
3. In the support article: If you subscribe to Apple One and use a different Apple ID for iCloud - Apple Support Apple alludes to using a different Apple ID just for media, subscriptions, and purchases, but doesn't describe how to do this. See if these work:
In iOS/iPadOS: Go to Settings > [your Apple ID] > Media & Purchases. Sign out of the current ID and sign in with a different one.
In Ventura or later: First, quit Settings. Then, in App Store, choose “Sign Out” in the Store menu, then click on the “sign in” button that appears in the main window. You can then sign into the other account. (from: Using different Apple ID for media & purc… - Apple Community )
Related to that is: Use a different Apple ID to share purchases with Family Sharing as outlined in Use a different Apple Account to share purchases with Family Sharing - Apple Support
