Practice conversing and talking.
Socialising is a muscle, and smartphones (and other devices) are a crutch that lets us avoid using that muscle.
When we eat out we try to do the same but because of the damn menus, translation app, etc. the screens still come out. We still are usually doing much better than the other tables in the restaurants. Helps to turn the devil device face down.
We think it is just so sad to see people out on a date, or even a clearly married older pair, each staring at their (own) screens.
Then within those categories you have easier and harder games (and better made or less better).
Try a sampler platter and see what works and is fun.
Some specific suggestions:
Love letter, Takanoko, munchkin, elder sign.
Staying in touch with friends, finding new interesting people, browsing local events, deciding where to meet, etc.
The problem is when you are just "on the phone", not really doing anything, not anything you planned to do, and not really getting anything done. Even this can be fine, as long as you go "I'd like to see whats on twitter for half an hour", rather than just opening things up and doing them because the algorithm pulls you in.
There's nothing wrong with smartphones per se. It's that the smartphones become a crutch to avoid socializing in person. All the excuses come out to prevent that crutch from being removed.