Make sure they're fully informed about what universities want. I taught a pupil one time who picked chemistry, French, and something like textiles, as they were her favourites. But most French degrees wanted an essay subject as well; most chemistry degrees wanted another science, and so she by default ended up in the creative path - which is fine, but wasn't a choice she realised she'd made age 16 ,and said later that she might not have done it had she really realised what she was choosing. (She was warned, but she took the advice of 'choose your favourites' very strongly, and wasn't keen on advice).
I also know a law tutor at Cambridge who said that they don't particularly want Law as an A-level (gives the wrong idea about what univeristy law will be like, apparently) and choosing Law and a couple of other unrelated A-levels is actually a worse combination for entry than a mix of a couple of good essay-related and/or logical thinking A-levels. But unfortunately those with less experience with university, particularly Oxbridge, and less good advice, were the ones more likely to choose those subjects because on the face of it, it sounds sensible. And those are often the groups they were trying to encourage to apply to Cambridge - people who didn't have a strong family background of university, those at schools without experience of sending many people, etc. So she was quite keen to do outreach about what A-levels were more or less useful. However, that was quite a few years ago, before the idea of 'facilitating subjects' became less of a thing, and other aspects of the A-level and University courses could well have changed in that time. I think Pyschology can suffer from the same problem - what university psychology departments often want is biology and/or maths and/or essay writing, and really aren't fussed if it's psychology (though I don't think that one is as actively un-wanted as Law, just not particularly needed).
So make sure she really has done research about the university options, even if it seems so far away to a 16-year old who may have no idea what she wants to do - just know what are good combinations or not could still be helpful.
Beyond that, yes, let her choose