My daughter took a couple of years out to get experience before properly applying this year as she was told that drama schools wanted students to have a bit of life experience for BA Acting courses. She also did the BOVTS foundation course at 19 - there were only 2 her age and the rest older.
At LIPA she was probably the oldest on her audition day, with many of them still in sixth form. Some of the schools held later auditions by zoom so hard to tell but she was the norm at RWCMD, and Birmingham and at Guildhall, while there were others her age there was definitely a large proportion that were several years older.
We did look at the LIPA stats and apparently 15% of their students are “mature” (22+), if that helps. I think if she’s offered she may speak to Admissions to find out the age range on her course to see if there’s a bit of a mix. x