It is shown that every automorphism of a classical unital over a certain (not necessarily commutative) field is induced by a semi-similitude of a corresponding hermitian form. In particular, this is true if the form uses an involution of the second kind.
"Automorphisms of Unitals." Bull. Belg. Math. Soc. Simon Stevin 12 (5) 895 - 908, January 2006. https://doi.org/10.36045/bbms/1136902624