Ours are now a bit older - 17 and 20. So - on the one hand, I have no experience of kids who have lived an "always-digital" life. On the other, I feel I've learned quite a lot about how to think about this in a feasible / managed kind of way, and I think (?!) that we've emerged with two reasonably balanced kids who have both "real" and "digital" lives and a somewhat realistic world view. As a concerned nerd I've also been on the case from the beginning, worrying about it, trying different approaches, etc.
My strongest opinion is probably about the age that kids are exposed to this stuff, and the role that parents take (or - more often - don't take) in defining what is ok and what isn't ok. The headline here is that kids have too many gadgets and too much exposure to the online world, and they have this too young. IMO, it is not ok for a kid of 7 to be spending all their time looking at screens, let alone a kid of 3 or 4. I mean, really, I don't think it's ok for my son of 20 to be spending all his time looking at a screen either - but in that I now have limited (no) control :-)
In this - sorry - but parents of younger kids are often complicit. Granted, we all face huge pressure from all corners and I totally take on board that social media and the digital world in general is built in order to make us addicted, and our individual power is limited. But... parents often don't say no enough. It's understandable - they're tired, the kid is kicking off, pop a screen in front of them, job done. But - parenting is hard, and it's always been hard, and you have to work at it - whether it's learning to read, fixed bed times, eating vegetables. Letting your kid get away with stuff is going to bite you / them on the ass at some point. A screen is not a golden bullet, and as we all know it's also often actively harmful. So, sometimes you'll have to say no, and the kid will cry, and you'll be the bad guy - but that's ok. It's always been ok, it's not abusive, it's about setting sensible boundaries.
The thing is, you're not going to stunt your kids' social life or anything else by not letting them have a phone until they're 13 or 14. And - tough if they say "all my mates have them" - that's been the argument since I was a kid and Matt over the road had a Grifter and I didn't. My mum didn't take that shit back then and nor should parents now.
The "but all their friends are on there, it's how they communicate now" thing - I mean, yeh. But - if I'd spent 20 hours a day talking to my mates on the phone or even in person my mum would have (rightly) freaked out. It's not ok, and until they're 16 or 17, and even beyond! - it's ok to express your opinion and apply pressure as much as you can within the constraints of your world / network. After all, you're (probably) in charge of the PiHole, their phone payments, whatever - so you do have an element of control. And as the old trope says - "while you're living under my roof, you play by my rules"...
In practical terms - no phones in bedrooms, limited screen time, no screens (ever) at the table during mealtimes, some parental monitoring of what apps are installed, keeping tabs on email inboxes for younger kids. All the usual stuff.
Finally - lest I sound like a loon - all of this should be done with open dialogue, even from a very young age. Talking about access to pr0n, safeguarding, why unfettered access to social media isn't great, what harms this stuff may do, why you know better as a parent - all of this is best done in an open, friendly way. Open and friendly does not equal "parents are a pushover" - but this works best in my experience when you're very honest about why you have concerns and are applying the controls that you're applying.
Good luck out there.