There's a type of puzzle called Hanjie. They are Japanese picture puzzles, where you colour in squares to make a picture, using a grid and numbers around the edges indicating how many squares to be coloured in. Once I start doing these I can't stop. I particularly like Super Hanjie puzzles, which are bigger.
Even watching people doing colouring in, can be relaxing. Sometimes I watch ASMR videos on You Tube, and one of the things they show is people filling in colouring books.