More general 'increased beauty'

[bstgate]

"Mrs. Braithwaite" by Geneva

These stories about a coven of witches revolve around a spellbook, where one spell in particular causes all men who hear it to become beautiful women, and all women who hear it become more beautiful and youthful. Needless to say, most witches use it on themselves.

Chapter 1
Chapter 2
Chapter 3
Chapter 4

[bstgate]

Originally Posted by bstgate

These stories about a coven of witches revolve around a spellbook, where one spell in particular causes all men who hear it to become beautiful women, and all women who hear it become more beautiful and youthful. Needless to say, most witches use it on themselves.

Apparently pretty much all stories by that author feature that book as plot device. Although all feature TG, far from all include any female IB.