Yep, let them get a bit bored. They will soon think of something to do.
DD is 7 and loves playing mummies with her dolls, schools with dolls and soft toys, zoos/safari parks with soft toys and dolls etc. Dolls don't have to be dire - they're just objects to use as you want to in a game and can be great props for imaginative play. I am the headteacher/zoo keeper/grandma in these scenarios and have minimal input.
If they aren't into imaginative play, then junk modelling is good - give them a load of boxes and paper and glue and ask them to make something. If they have no ideas, give them some - a house or a car or a rocket or a cave or a robot or whatever. Working out how to do it is part of the fun.
Lego or sticklebricks or similar have endless applications.
Get a big box and a couple of old newspapers and tell them to build a nest for baby birds (they are the birds). Then they can make some eggs and sit on them and they can make the even smaller birds, too, when they're ready to hatch.
Mini golf inside. But they have to make the holes, the golf clubs and the balls from whatever is available.
Invent a board game (they do the inventing and you can work out together if it's actually playable or not).
Craft stuff from the internet. There are a ton of printable things that you can make. DD just made a Hallowe'en basket for trick or treating with no input from me apart from her asking if she could print it out on thick paper. She found a plan online, printed it, coloured it in, cut it out and stuck it together. She is really proud of it! It is not the most polished piece of work, but that's not the point. She feels great for having had a plan and carried it out to completion - and can't wait to actually use it.
Music - get a little cheap keyboard, a ukulele (you can get them really cheap), a recorder, a xylophone, whatever, and let them make up a song to perform to you. Or a play to perform to you if musical instrument buying is a bit expensive. They can record themselves on your phone or on a laptop and play it back. DD did this with one of her (really v tuneless) songs and I put it in our music library under her name as the artist and she is really pleased with it. I even imported a photo of her as the cover art.
Dancing to music. Any old music will do. Spotify will supply plenty of suitable playlists for children and you probably have CDs that they'd like.
Chores. Give them tasks to do. Put own clean clothes away. Wash the bath (this is actually brilliant fun if they wear wellies, get into the bath, and just use something fairly non-toxic like soap). Mop the floor. Hoover. You do have to supervise but at least something useful is being done.
Buy a roll of lining paper and get them to create a tablecloth for your table (they will have to work out how to make it the right size and shape as well as decorating).
My DD also has no idea about minions or carly or whatever but it hasn't stopped her being able to play.