I've had trouble finding watch bands that were large enough to fit comfortably.
It seems like most of Apple's official watch bands are designed to fit a wrist in the 160-180mm range. My wrist is more in the 210mm area. The problem I've found is that while finding watch bands that "fit" 210mm or more is possible, it usually means I have to wear the band on its last hole or otherwise on its largest setting, which doesn't allow it to close correctly (you can't tuck the end of the strap into its loop if its on its last hole). So, basically I need to find watch bands that fit well beyond 210mm.
What I found that fits well:
* Apple's official "Sport Loop" band. ($49)
It says that it fits "145 to 220mm" wrists.
* Shinace Leather Strap ($13)
It says that it fits "144mm to 234mm" wrists.
Yunsea Sport Loop, $10
https://www.amazon.com/dp/B07B4T3FGJ/
Carterjett, up to 11"
https://www.amazon.com/dp/B06VX29551/
iStrap
https://www.amazon.com/dp/B01F71T7FU/
6.8-8.2inch
Fintie
https://www.amazon.com/dp/B07D7PKHGF/
6.10"-8.66"(155mm-220mm)