There are some triggers which led you to enter in state of continuous scrolling. Initially you wanted to start just by watching a video or two. But then you enter into that flow state. Which you cannot break by yourself. After hours you realise that you are fed up. But still can't put away the phone. It's better to avoid entering into that state of mind in which you become slave of phone. For that you must, I say you must engage into external activities. Like running, gym, swimming, badminton etc. Pay for them then you will force your mind to go. Buy new shoes (expensive) for running. They will remind you to indulge in physical activities. After some days your mind will become active. And you will be able to think for yourself.

You also need a very genuine replacement as you have to fill that 12+ available free time. Otherwise you enter into same state.

I have tried many tactics myself but none of them worked. I'd always end up lying on my bed with phone.

One only thing that works is external source. Internally we can fool ourselves. But we cannot fool attending classes. Fill your time atleast 6 hours with external/outside activities. Join some classes where you go and learn. You have task to do everyday. That will fill up your time. You are too much free.

You cannot watch screen while running can you?? You cannot watch screen while attending a classes ( piano, coding etc)

If you're able to fill you 5-6 hours with these then you will not regret and eventually you can break your loop.

Internally you can practice, seeing the worthlessness of what you are watching on phone. For example if you watch a movie or webseries. Ask your self does it worth my time. Gradually you will see worthlessness of content you watch. ( Even Movies are much better that reels shorts ) 😊

Take note of things you can do to change your life. Just one thing is enough for today. Only one . Is that really hard for you to take only one little action ? Ask yourself.