Forgive the ramblings, but hopefully this will make a coherent bit of reading at the end.
This is all based on personal experience (and I'm not a pro).
If she's thinking of upgrading to a FF body in the future (no matter how far off), then most (but not all) lens purchases should be EF lenses. Not all EF lenses are L series lenses, so they're not all mega-bucks, but it makes them future proof. If, on the other hand, she decides to keep both cameras (Full Frame and Crop) then a bit of mix and match isn't a bad thing.
When I got my first camera, I had no strategy for buying lenses (didn't think I needed one) and fell victim to a fair bit of GAS (Gear Acquisition Syndrome). As a result, I ended up wasting money on some things. I also had in my head that the first thing I should upgrade would be the body, but in fact it should be the lenses. A cheaper lens on a good body will drag the quality down, whereas a good lens will always be a good lens.
You didn't say which kit lenses your daughter has, but it would be interesting to ask her to look back at the shots she's taken and see which are her most used focal lengths. I didn't do this, and hence ended up buying lenses that incorporated focal lengths I didn't need. My kit lens was the 18-135.
I'd assumed it was rubbish as it was a 'kit' lens, and soon after bought an Sigma 18-250. This turned out to be a mistake. The Canon lens was sharper, and I ended up selling the Sigma lens when I sold that camera and keeping the 'kit' lens. However, I will say that I loved the flexibility of the lens and it made a great 'walkaround lens*' for holidays and the like as it offered versatility without the need to change lenses, but at the cost of ultimate image quality. It also produced ugly bokeh.
One of the first lenses I bought was a 50mm 1.8. Because everyone said 'you have to get a nifty 50'. And I loved it at first, but it seemed to go 'off' fairly quickly. Same lens, same camera, it just didn't produce sharp enough images towards the end. I also found that it wasn't quite wide enough*. I normally take a camera to events I'm part of (rather than shooting an event for someone else) and when you're indoors, I could never quite get far enough back in many situations. But I did love the f1.8.
In the end I replaced it with a Sigma 35mm f1.4 and found this to be much more useful* - extra light gathering as well as being that little bit wider (though it was a lot heavier). However, this is an EF-S lens, so would be useless if I then went full-frame.
Since being on here, I've tried not to duplicate/or replicate focal lenses where possible. So my strategy (such as it is now) was to try and cover lots of focal lengths without too much overlap or gaps.
Hence the latest lenses I've bought have been 10-22, 24-70, 70-300.
One of the things I would say about both of my non-canon lenses is that they represent great value compared to their Canon equivalents. My Tamron 24-70 2.8 was £700 new. And, in the reviews I read, doesn't lose out much to the Canon L lens in image quality. Where I struggle with it is that I'm sure I read a conspiracy theory that said Canon design in lens- recognition software so that their own lenses are quick to focus, whereas third party lenses aren't. There are definitely times with both my Sigma and Tamron lenses where I have to repeatedly press/half press the button to try and force it to focus. This doesn't happen with any of the Canon lenses. Not so bad for me as an amateur, but it might be a deal-breaker for someone thinking of becoming a professional.
The next most useful bit of kit for improving indoor shots is a flash. While it's true that you can't use one everywhere, a flash (even on top of a camera - as opposed to off-camera) would certainly be a worthwhile addition to her kit if she's going to be shooting indoors. Especially with a lens that doesn't open up beyond f/4.0.
My first flash was a Canon 430EXII - which I like, but (again after joining here) I found out you could get something as good for a lot less. I'm not completely up on what's what, but Yongnuo and Godox seem to be the standard alternatives, with Godox (I think) coming out as best for reasons which currently escape me. My last flash was a Yongnuo one I bought on here for about £60 (SH) versus a new price of over £400 for the equivalent Canon flash.
In summation. The best piece of advice i ever got on here is to work out what her current lenses are stopping her from doing and then go from there. For example, although my other lenses cover 24mm, I bought the 24mm pancake lens for times when I'm going out to dinner and don't want to lug about the 24-70, as it's heavy and bulky. The big lens was stopping me from taking my camera out. So that lens was bought for a specific purpose which I only discovered after using the other one for a while.
I'm perfectly happy for other people to contradict everything I've said above, TBH I expect it as I'm by no means an expert, but just trying to help someone avoid the same mistakes I made.
*For me.