Do you have some kind of app(s) running in the background eating up your battery? Especially location services. I have all of mine set to “while using” except Weather which is always. Or are you in a location with poor cellular reception?
There are certain spots I’ll drive through where I notice my phone gets pretty hot but I’m not entirely sure why. Probably cellular. But running wireless CarPlay using Apple Maps GPS and playing Apple Music, my 30-minute drive home from work can eat about 5% battery on good days, or like 10-15% randomly on bad days, just haven’t figured out why. I think it could be social media. When I make a habit of force closing Facebook and Instagram when I’m done looking, it’s usually fine afterward. I think also The Weather Channel can get it cooking as well. Can be annoying, but I accept the trade-off solely for the amazing form factor.