2 games I made up years ago for zero outlay which are remembered fondly:
Your Car, My Car. Sit near a road (!) Take it in turns and look at the vehicles coming in one direction (too confusing to include both directions). So you know who is going first, second and third. The first person would "win" the first car, the second person would win the second car to drive past etc. This always cheered us up when someone won a Jag then the next person had a dustbin lorry! Can be played anywhere where you are stuck waiting in a car or by a road.
Bed game. This is a bit bonkers. Get 2 people to lie in a double bed under the covers. The third person has to dress up or think of something scary to do and creep up on the bed people then throw the covers off them and they look up and are frightened! 😂Awful things we thought up were lighting your face from underneath with a torch, wearing a cyberman mask, wearing my dressing down up over the head like the grim reaper etc. You can also make creepy sound effects as you walk towards the bed.
Make lanterns from jam jars with coloured paper glued round.
Turn off the electricity and sit in the dark with lanterns going and cook on a camping stove or on a tin over a candle.
Treasure hunt with post it notes. Number the notes in case they find them in the wrong order. The first would say something like "the coldest place in the house" then they would find note 2 in the freezer etc.
Let them sell their old toys or anything you want to clear out on FB marketplace.
If you have a village show locally, enter all the children's classes which will be things like drawings, sample of handwriting and so on.
Make a timelapse video (can't remember the software now but it is free) with lego or playmobile figures. You can build a jig for the phone to stand on out of lego.
Make an actual video where they are the actors. My children liked making props.
Make a cardboard box dolls house but go completely over the top and paper it with wallpaper samples and make curtains from old clothes cut up.