I would be interested in knowing if you have tried to fit a 27.5" wheel into the rear dropouts with a reasonable sized tire.  Now that you have the bike you can know if it would fit.  That woudl really make this a perfect upgrade frame maybe.

With 26x2.25 Schwalbe tires, there is about 1 3/8" clearance toward the bottom bracket. Could work.

Seems to be a Leadnovo frame, same as these two:

https://www.aliexpress.com/item/Carbon-Frame-2018-super-light-Mountain-Frame-29er-27-5er-China-Chinese-taiwan-race-carbon-fibre/32854396087.html?spm=2114.11010108.06001.6.650c649bDBwHax&gps-id=5347592&scm=1007.13562.109986.0&scm_id=1007.13562.109986.0&scm-url=1007.13562.109986.0&pvid=f94be5f5-85de-41b8-bd3b-cc3b01b2466e

https://www.aliexpress.com/item/Leadnovo-Carbon-mtb-bike-LN950-carbon-mountain-bike-frame-27-5er-29er-UD-PF30-bicicleta-mountain/32795738080.html?spm=2114.10010108.1000023.9.dbd8288eWdIjBU

My daughter is 11 and the same height. I built up a 26er this spring with this frame:

https://www.aliexpress.com/item/Cheap-price-stock-frame-2014-cube-frame-mtb-bike-frame-cube-mountian-bike-frame-size-14/32249756705.html?spm=a2g0s.9042311.0.0.1a694c4d4BbChj

Note that it takes a 27.5 fork, and the chainstays are only 5mm shorter than the similar 27.5 frame, so I'm thinking this frame is not really a 26er, but more like a 27.5er. If that appeals to you, go for it, because it was a nice frame to build up and inexpensive.

I wanted a 26er because I had some nice 26" wheels from an old race bike I could use. As she grows, we might get a little more use out of it by putting 27.5 rims on it with a longer stem.

Some others here have gone with the Tideace FM-M001, available from multiple sellers. There is a thread in this subforum on a build with this frame. If I did it again, I might go with this frame. That said, my daughter is quite happy with her bike. Built up, it's about 21 lbs, and that is a huge advantage for her over heavier kids bikes which can be north of 30 lbs.

A larger one at the front does the same thing.

Okay, went with the first one, with a 490mm specified fork length, and got a 27.5 fork to match (495mm). I'll sell the 26" fork locally.

The frame is very well finished. It's a 71 degree head angle, but I don't consider the 1 degree difference to be a dealbreaker. I like the internal cable routing for the gears. I'll keep the brake line external. This frame, I'm sure, could accept a 27.5 wheel. In fact, they sell an almost identical 27.5 frame, and the only difference in the listed geometry is 5mm longer chainstays. I measured mine, and they are 425mm, as listed for the 26" frame.

All in all, this is coming out nice.