Hello @andreas bright
Thank you for reaching out to us.
In order to view Authentication methods register for user you need to navigate to the path provided in the below screen shot.
And in order to enable the MFA you can do this by enabling conditional access policy for all user or you can also enable it through Per user MFA both methods paths are provided in the below screen shot.
Enabling Conditional Access Policy
Per User MFA Enabling
In case you have any questions on the same, you can surely let us know and we will be happy to help you further. If this post provides you the answer you were looking for, do accept it as an answer in the interest of community members with similar queries. If this does not answer, please ask further in the comments and we will happy to address your concerns. Thank you.