1) Only allow notifications for texts, calls and maybe email.
2) Only allow yourself 1 screen/page for your apps. Extraneous stuff should be in folders. I have my most-used apps and 4 folders on a single iPhone homescreen (Shopping/banking; Food; Extras; Games).
I'm the last of GenX and remember many years without cell phones. But I feel bad for Millenials who never knew anything else and will probably never learn to really get control over these devices.
If I could get a T9 cellphone with voice dictated mapping built-in, I'd dump traditional smartphones altogether. Having your devices work for you rather than work you over is a huge part of the 21st century. So says grandpa.