You can match most bands with any Apple Watch Series 3 or later case of the same size.
40-mm, 41-mm and 42-mm bands are all compatible with 40-mm, 41-mm and 42-mm case sizes. 44-mm, 45-mm, 46-mm and 49-mm bands are all compatible with 44-mm, 45-mm, 46-mm and 49-mm case sizes.
The Solo Loop and Braided Solo Loop bands are only compatible with Apple Watch SE, Apple Watch Series 4 or later, and Apple Watch Ultra or later.
For Solo Loop and Braided Solo Loop, the 40-mm, 41-mm and 42-mm cases are compatible with band sizes 0–9; the 44-mm, 45-mm, 46-mm and 49-mm cases are compatible with band sizes 0–12.