I don't know what age your kids are, but it'll be a difficult struggle when the time does come.
I've got 4 step kids, who are 11, 13, 16 and 18. All aside from the eldest have smartphones, (they have each had them when they have gone to secondary school), and it's a constant problem - probably the thing where I have the biggest disagreements with them (I have an excellent relationship with all four of them, and they're all good, intelligent kids).
It's like a disease, and it's insidious. They are completely unaware that they are being manipulated by the software that they use every day, and are addicted to their phones, being connected and the Fear of Missing Out (FOMO). I have spent many an hour trying to tell them that nearly everything they use isn't agnostic about its behaviour, but that it tries to manipulate them into spending as much time as possible in the app/site and so on.
I've really cut down on the amount I use my phone over the last year or so, and it has paid huge dividends. About 18 months ago I stopped using Facebook, and any other social media. I feel massively better for doing so, but it took me a long time to break the habits; and I'm a 46 year old with a brain that developed without such patterns as the norm, and I'm told I have 'immense self control'. So how on earth is a kid who doesn't know any different supposed to be able to do anything different?
I'm sure I'll get shot down by some (or downvoted), but I think there's a huge difference between technology itself and the way that it's being used to manipulate. There are always the arguements that 'you don't understand the modern way' - that being connected and always on is the norm... or that I'm a hypocrite as I use computers at work.... or that it's OK, and it means throwing away the ability to look at Wikipedia... but the truth of the matter is that most of the time spent isn't enriching yourself, it's flicking through instagram posts like a cat pawing at a washing machine.
I'm particularly concerned about the 13 year old, as she appears to be going backwards in terms of reading age and ability, and her attention span is dismal. She used to like reading, and now she complains that any book we suggest is 'too difficult' and the stories are 'too long and complicated'. And we're not talking 'A Deepness in the Sky' here. Particularly tragic as she was extremely creative (far more so than the other three), but seems to be getting less so as time goes on. Don't get me wrong, she's not stupid, but she seems to be diverging from the path she could be on as time goes on, but spends hours looking at junk on her phone.
Meal times are always device free, which works well. There's (now) one place in the house to charge your phone, and if it's on charge, you stop using it until it is charged.
For about the last 6 months we have had Sunday nights as completely 'device free' - from 5pm, every computer, ipad, phone, etc., gets turned in, and no-one goes on anything (yes, me included) - no TV or anything. And it works brilliantly well; there is nearly always some resistance at first (and the first month or so was difficult), and some moaning, but everyone acknowledges that we've had some of the best times as a family when we've been completely without any distractions; sometimes we will play games, sometimes we will have discussions, sometimes we will read, or do something individually or in small groups, but it's a complete change from the usual time where most of the people in the household are disconnected in some way, or distracted.
The eldest is at University, and is obviously an adult, but when she's home she plays by the same rules, and has also (in the last discussion had on the subject) admitted that when she got a phone (6 years ago), it was a completely different landscape; it wasn't weaponised against the user as it seems to be now. She said in no uncertain terms that it's not suitable for her youngest brother in the way it used to be, which was interesting, but she still doesn't agree that being device free an evening a week is a good idea.
Anyway, one of my biggest worries as a (step-)parent is that I will not have done enough to protect my kids' minds against the tobacco of our age, particularly when I've been reading about how bad the problem potentially could be. I sincerely hope I'm exaggerating the risks, but I doubt it.