Welcome, @dransel to the community!
I am able to autofill usernames, passwords and even use passkeys from Bitwarden on my iPhone, both when using Safari and Chrome. Instructions here.
Individual browser extensions are not needed (nor supported) on mobile devices. Instead one installs the Bitwarden iOS app from the Apple App Store (Android as similar). The app is capable of autofilling all by itself.
I would like to add some corrections here: Safari on iOS does support extensions (see the 1Password example earlier in the thread). As to why one would want the extension over the app - the app doesnât work perfectly well. I encounter many websites where the autofill doesnât work properly. In those cases I have to minimize my browser > open Bitwarden app > search for my password and copy it manually > return back to the browser to paste it. With an extension this becomes a much simpler process.