Depends on the level of resort.
When we stayed at POFQ, they had a large towel trolley at both main entrances along with used towel receptacles.
We just returned from a stay at POP. They did not provide towels at the pool but you were supposed to use towels from your room. However, in our building at least, they left a large towel trolley on 2 of the landings for guests to use at the pool. I'm guessing it minimized calls to Mousekeeping for fresh towels.