Can I convert a 240v hot tub outlet to 120v?
Usually it isn't too difficult, most hot tubs are fed by a 4 wire connection: a ground, a neutral, and two opposing 120v hots. Either of the hots can be connected with the neutral to create a 120v circuit. The two hots can also share the neutral creating essentially 2 circuits in a configuration called a multiwire branch circuit. Since they use the same neutral the breakers need to be handle tied or fed by a two-pole breaker. The tub was already on a two-pole breaker, but you need to change the breaker size(s) to a 15 or 20A, since those are the largest sizes allowed for typical receptacles or general purpose lighting.
The biggest complication is the existing boxes may be too small. The NEC has specific calculations of cubic inches for size of the box based on sizes of wire and devices in the box. Too complicate things the wire that fed the tub is too big to terminate in the terminals of a typical receptacle. You have to pigtail them off with smaller wires to fit the receptacle. You don't have to add inches for the pigtails that start and end in the box, but they still add bulk. Plus you wan't to add some wires to go off and feed another location and those do add to the count.  It's easy to select a box that's too small.
Outdoor receptacles require GFCI protection, you can use individual receptacles or a gfci breaker to satisfy that requirement.