As contra productive as this may sound initially, there are apps for that.
If you have any idea how much time per day you want to spend on certain apps (with the time amount for studying in mind), you can set perimeters for those apps (Insta, YouTube, Netflix, Facebook, etc.).
That way you get warned before the number of minutes/hours are almost finished.
After that they’re closed for the day (that is, those pesky apps).
You can circumvent it, but that would mean kidding yourself.
You need to be dedicated (which you already might be because you came here to ask about it).

Put your phone in the mail to someone who cares about you asking them to keep it safe and hidden for two years. Do life without it. You’ll find much of it is easier and no one, and I mean no one, needs to be accessible to the world at large 24/7. Take care of yourself. You aren’t alone.

I find @SnipSnip‘s answer a bit extreme and probably not something you’re going to be able to do. However, I do suggest you put it away from you somewhere out of reach for a certain portion of every day or at a certain time each evening. Get used to time away from phone.

Or follow @rebbel‘s suggestion and use the shutdown apps to cut yourself off.

Give it time. Odds are, you’ll soon either tire of the routine or abandon it in disgust.

Hide all your chargers/cords. Let the phone die.

Start breaking up the habit times. Wake up and check the phone gets changed to Wake up and walk the dog before touching your phone.

Set goals of breaks from your phone: wait 15 minutes between touching it. then make it 30 minutes. Then 10 minutes. Then 25 minutes. Then 40 minutes. Then 30 minutes. Eventually you will have no routine.

Replace using your phone with something else you like to do to get out of the habit. Go to a dance class, go swimming, meet up with friends, go to a lecture, whatever interests you.

Don’t always have it right next to you at least part of the day. Put it in another room or out of reach.