Is it safe to install Apple's latest iPhone software, iOS 11? If you don't like it, are there options to remove it and go back to the old system?

Apple iOS 18.6.1 is compatible with all iPhones from 2018 on. That’s the iPhone XS, iPhone XS Plus and iPhone XR models and ...

Testing with developer and public beta versions went smoothly for even the oldest supported models. But there are safety measures if upgrading to the beta or release version goes awry.