Bitwarden through 2023.2.1 offers password auto-fill within a cross-domain IFRAME element. NOTE: the vendor's position is that there have been important legitimate cross-domain configurations (e.g., an apple.com IFRAME element on the icloud.com website) and that "Auto-fill on page load" is not enabled by default.
Bitwarden through 2023.2.1 offers password auto-fill when the second-level domain matches, e.g., a password stored for an example.com hosting provider when customer-website.example.com is visited. NOTE: the vendor's position is that "Auto-fill on page load" is not enabled by default.