There's a saying that, "out of sight... out of mind." Thus, remove those applications or unsubscribe from platforms that taking your extra time.
Android offers Digital Well-being and iOS has Screen time. You can use these applications to restrict applications' time to reduce screen time.
In your bed, don't use gadgets such as TV, tablets and obviously smart phones. This will help you sleep more and reduce screen time.
Make your morning routine without smart phones or gadgets. Include meditation, Yoga, and other mindful activities.
By reading or viewing long form content, you'll tire your mind for good and this will make you avoid more screen. Hence, reduced screen time.
With notifications off on mobile phones, we can focus more on work without looking at the screen now and then. You can also lock the phone in the desk cabinet.
On the weekends do digital detox. Give time to yourself and family. Try some hobbies or new fun activities without increasing screen time.