dude, yes it would, thats literally the point of nintendo switch online, to make online only games restricted behind a 4 dollar membership, it may or may not require nso (because its a 3rd part game) or it might if innersloth and nintendo strike a deal.
if a game requires online access to play (fortnite for example) it doesnt require switch online. No online only games have and no online only games every will because that would cause people to leave nintendo and never return, which is a terrible business decision