The general recommendation is that at that age he shouldn't watch more than an hour a day, and preferably less. What happened is that the phone became a crutch for both of you - it's easier than dealing with the crying, but now your son has less tolerance for frustration and gets bored without constant stimulation, so toys seem boring to him. The tricky part is that you can't quit screens cold turkey without consequences, but you can start cutting back gradually: maybe tomorrow it's an hour, next week 45 minutes, and in the meantime you reinforce other activities - drawing together, building with big blocks, playing outside even if it's just 15 minutes. At first he's going to cry more, but at that age the brain adapts quickly if he sees there's actually something more fun available.