I had my tomcat wearing a collar when he was only 8 weeks old, he’s worn a collar since.
Eventually because of our outdoor off the grid lifestyle I started using a locating system for him with an old school electronic located that would locate a transmitter on his collar. The collars had the antenna woven into them and they were the break away type, the only option, so I didn’t expected them to stay on but he’s worn those locating collars for years, for some reason they stay on. Maybe it has something to do with a cat fighting wearing any collar they wear.
Anyhow, considering your situation, as advised I’d make certain they’re microchipped, and have collar with id, or a locating collar. They have gps locating collars that I’ve read work well, you can use an app and see exactly where your cat is on a map.
I’ve never used one as our old school transmitter system has done well for us. It’s a good system and not reliant on tech or satellite signals.