If it's not too bad, a buff/polish/wax should bring it back. As it ages, gelcoat requires continual upkeep to stay shiny. The longer you let it go, the more it takes to bring it back and the shorter the time it stays shinny.
If it's really bad, I would suggest you consider painting. We used interlux Brightside on our last boat (easy DIY but prep still important) and when we sold it 4 yrs on, it was still shinny with no buffing or waxing at all for 4 yrs. For a simple area like an end cap, it's probably not much more work than a serious buff and wax job.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV