Beach trips, camping for a couple of days, or they could take turns hosting at each other’s houses and either playing board games, videos, movies, water balloon fights ….

lazer tag

Try different sports by approaching local clubs.

Outdoor adventure activities can be good and often these are run by community organisations.

I would suggest getting them to write a list of the things they like to do.

Trees adventure parks. Depending on where you live there could be one. This is the one we have visited in WA. So much fun!! https://treesadventure.com.au/park/lane-poole-park/