I have some extra buttons on my mouse that I would like to reassign. Any software to do that on Windows?

Can look at Power Toys, in case Key Remapper can recognize those keys.

If it’s a logitech, they have their own software for that (logitech options)

Logitech G Hub. It works on both Windows & Mac. I am using G402 mouse. Prior to that had Circle Marksman 2, which had it's own software.

It's not a logitech mouse 😞