It depends is the honest answer.
Road/CX bars don’t really have a massive range; they tend to come in 38 (which is very narrow/small) through 40, 42, 44, with the vast majority being 42 or 44. there are wider bars, but the are less common.
Be aware that different manufacturers measure things differently; some are 42 outside to outside, some are 42 centre to centre.
To be honest, whatever bar you buy and get used to will be what you like best, then when you change to a wider bar you will feel ‘wrong’.
I’ve got FSA omega compacts on road and crosser, 40 c-to-c on road, 42 c-to-c on cross.