@AintPageantMaterial
If you send her to a school that she is clear she doesn’t want to go to then, every time things get difficult (as they inevitably do at school), it will be your fault.
At 16, you need sufficient enthusiasm and commitment from her towards anything new or it just won’t work.
This is exactly what I was going to say.
It needs to be her choice rather than you forcing yours onto her.
If you force your choice, she goes to the school or college you favour and it all goes tits up, then what? She will resent you. That's what. Surely you don't want that.
My three DDs made their own choices with regard to sixth form or other further education. Each of them did make the best decisions for them. Only DD2 needed some prodding from us as she just wanted to drop below the radar at 16 but the options really are to get work/apprenticeship or return to education in some form.
DD1 and DD3 both chose a girls' grammar school (the same one) and for DD3 that did involve a change of school for sixth form. It was a great choice, not driven by us at all really. DD1 went on to Warwick University and came away with a First. DD3 got into Cambridge this year and is thriving there. Really loving it so far. Both loved their sixth form experience and the teaching was excellent.
Your DD sounds in some ways like my DD1 and DD3 were in that she quite self-motivated. Let her make her choice. By all means point out pros and cons, but also consider ways in which she will be able to make it work (tutoring, if that is an option) or online study etc.).
It is your DD who will be spending the next two years of her life in this environment. That is a big chunk of time to commit to going somewhere where she doesn't believe she can be happy, whatever her reasons for it. Don't dismiss them.
There is a reason why it is the student who applies for the sixth form these days. It is their choice even though parents may have to sign some things off (really only a rubber stamping exercise).
I wish it had been a choice open to me back in 1982 when I was about to go into sixth form. Back then you didn't apply anyway. You just went back to your current school sixth form if you were not leaving school at 16, so sixth forms were a lot smaller than they are now.