Officially, Apple services are available to you in your ‘home country’. Apple Media Services terms and conditions - Apple Legal
Use of these services abroad may work or not work, and that may differ by service.
Notably third party in-app channels and connected apps will likely be restricted to use in the same country as originally subscribed.
Some users have reported that Apple TV+ has worked for them while in a certain different country, but don’t take that as policy or guarantee for every country.
Some users have reported that iTunes Store movies has worked for them while in a certain different country, but don’t take that as policy or guarantee for every country.
If you download media files on your devices for offline use, then those should be valid for 30 days.
For Apple’s official stance on such use, contact the Apple Support staff.