I’ve met two girls named
Nicole and they were both British and in their 20s.
Nikola is a male name here and I know numerous boys/men all ages named this. The younger ones are sometimes called Niki or
Niko. The female form used here is
Nikolina.
I prefer
Nicole for a girl in English and
Nikolina here.
Nikola is only male to me.
BTW, I live in Croatia.