You can match most bands with any Apple Watch Series 3 or newer case of the same size. (For Apple Watch Series 3, the 40mm band works with the 38mm case; the 44mm band works with the 42mm case.)
The Solo Loop and Braided Solo Loop bands are only compatible with Apple Watch SE and Apple Watch Series 4 or newer. Bands will only fit the selected case size and are not compatible with other case sizes. For example, a size 5 for a 40mm case does not work with a 44mm case, and vice versa.
Aside from case size, most bands come in various lengths as well. For more info, see:
Buy Apple Watch Bands - Apple
Select a band type you are interested in and then you can see what case and band sizes are available for that band type.