Ooh, I've actually done a weird amount of work into name etymology (though that was more with a view towards translation than genderbending) so I can offer a few options!
Suggestions to match the meaning/sound pattern of Rico have been well covered by @doesnotloveyou so I won't go over those again, but here are a few other ways to get a genderbent name:
Preserving the fact that 'Rico' is a nickname but not that it's short for 'Ricardo': 'Rico' sounds like it could plausibly be a shortening of Enrique, which has a fairly common feminine equivalent of Enriqueta, so a shortening of this could work.
Preserving the meaning of 'Ricardo': Here's my favourite bit which is also possibly the most useless :) So, Ricardo is related to the English name Richard, which has Germanic roots which basically boil down to good/strong/brave ruler. The most obvious word for 'ruler (female)' is 'queen', which is 'reina' in Spanish (similar to the English name Regina), so something from that could be a shout.
However, if we continue down the etymological path, we could use the fact that it has Germanic roots which were later Latinised instead. Specifically, Old High German. The Old High German word for 'queen' is apparently 'kuning-in' (similar to the Old English 'cyning' for king).* This... is a bit of a dead end! But the 'rih' component of Richard is the bit that means king, and though kuning-in has a masculinised form in 'kunig' there doesn't appear to be a feminine form of 'rih', so maybe we can keep that part and just look for other things to add to it.
Names that start with 'Ri' and have Germanic origin: mostly variants on Richard, Rico, and Ricky that we've seen before. Okay, this meandering wander down etymological lines hasn't really taken us anywhere new though. But fundamentally we know a lot more about 'Rico' as a name, so I suppose it's not entirely a waste. (Broadening the search a little to just include 'ri' somewhere gives us 'América' though, so though it's not really related, there is that if you really want it.)
If you want to preserve the 'vibe' of 'Rico', then I would recommend going to behindthename >> Ratings >> Similar Names >> Opposite Gender, although that can be iffy.
*While looking for German names with this as a root I came across a Reddit post suggesting 'Rhiannon' as a name meaning 'queen' though obviously that's Celtic in origin. As a Fleetwood Mac fan I'm obligated to pass this on, in case there's something to be done there.