Hello diana77007,
It sounds like you're looking for information about iCloud Keychain. If so, you can double check your current settings with the information below found in the article here: Make your passwords available on all your devices with iPhone and iCloud Keychain
"Set up iCloud Keychain
If you didn’t turn on iCloud Keychain when you first set up your iPhone, go to Settings > [your name] > iCloud > Keychain, turn on iCloud Keychain, then follow the onscreen instructions.
When you set up iCloud Keychain, you create an iCloud Security Code, which you can use to authorize additional devices that use your iCloud Keychain. It’s also used for verification so that you can perform other iCloud Keychain actions, such as recovering your iCloud Keychain if you lose all your devices."
The article here also has information to assist: Set up iCloud Keychain - Apple Support
The section "Automatically fill in a saved password" in the guide here: Automatically fill in strong passwords on iPhone, also has helpful information on how to use your saved passwords for websites and apps on your iPhone.
Hope the information helps.
Cheers.