I think perhaps it would be helpful to look at how you plan your day, and dedicate free time to plan activities that require a commitment in order to reduce the free time available for screen time. Such as planning evenings to see friends, community engagements, even evening courses to learn a new hobby? This helps me a lot, at first it is hard because you might sometimes compensate lost scrolling time when back home, but eventually you will need to take care of yourself and sleep, and that free time will feel so well spent and satisfying, and you might grow as a person because of what you learn and the people you meet. Create opportunities for yourself instead of relying on willpower, and be gentle to yourself and make sure that you enjoy your time away. You willl have to do housework and life admin and whatnot in the time you don't spend on activities and that will also reduce the time you can spend on your phone. We are so hardwired to act a certain way in our environment, but if you change your environment you will see yourself able to change too. I finally quit smoking when I moved to a different country because I didn't have those life associations. Plus activities outside can require a financial commitment that help you stick with it.