How to add a return or enter after password automatically

[grb]

No, but here is a Feature Request that you can vote for:

Automatically submit login form on auto-fill

Add an option to automatically submit login forms when an autofill action is performed. We might want an option to do this globally and/or on specific items. If we have a global option we would then also need an option to override it and disable it for specific logins too since the behavior may not be always desirable in certain situations.