I spent a while on this path - removing apps, hiding others, setting personal time limits or other restrictions on my phone usage. At each step on the way, all I learned is that I need to go further. Short of getting rid of your smartphone (which I have now done), the most effective thing I found was to make sure you put your phone in some fixed place in the house where you won't typically look at it (a shelf in the kitchen, in my case), ideally with it turned off. Even then, I would find after a few days that my phone was back in my hand and I had been wasting a lot of time on it.

There are no easy answers, sorry. You'll always find a way around any lockdown you do.