We like to wear simple analog watches. My children have narrow wrists so it's always been hard to find non-kiddie watches for them. Eventually I found a silicone wristband that wasn't too large for my 9 year old daughter on Amazon:
https://www.amazon.com/gp/product/B07SLX8P3K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
My older son wears this one:
https://www.amazon.com/gp/product/B07HJB27H8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1