The Alpine Loop comes in 3 sizes (S, M, L).
According to Apple, the bracelet size M is for 145 - 190 mm wrist circumference, I have 180 mm circumference and it fits well.
The Ocean is only available in one size (130 - 200 mm circumference, extension possible).
The Trail Loop is available in 2 sizes (S/M and M/L). S/M for 130 - 180 mm circumference, M/L for 145 to 220 mm circumference.
The easiest way is of course to try it out in the shop.

Hello erin48
48mm is the largest size