Typical sizes are inch, but newer stuff seems to be going to metric size wrenches on SAE fittings.
traditional inch JIC sizes for hose ends are:
-4 9/16
-6 11/16
-8 7/8
-10 1"
-12 1-1/4
-14 1-3/8
-16 1-1/2
It is worth having between sizes for jump size fittings or oddball stuff, more likely to see oddball stuff in tight places where some engineer used something goofy to make it fit.
For O-ring face, even with SAE threads many of the hex sizes have gone metric. These wrench sizes are from Gates
-4 17mm
-6 22mm
-8 24mm
-10 30mm
-12 36mm
-16 41mm