On iOS I’ve had good results with an app called Compress. It’s free (with ads) or $1.99 for the ad-free version.
This one is ad-free, with 2GB. Btw Don't pay for compression, underlying technology (ffmpeg) is open source & easy to implement.
Good advice. The convenience of the mobile app is nice, I will say. I just use the ad version. They’re short anyway. Lol. On desktop I use Handbrake which is of course free.