Keep one or more days screen-free each week. This takes focus off screen time as a default activity.
Have screen-free parts of house. Keep screens in public parts of home, not bedrooms. Applies to parents too.
Have children earn screen time, by co-operating including getting off-screen when asked.
Lead by example. Children are influenced by what we do much more than by what we say.
From Calmer Easier Happier Screen Time