The trick is to copy the folder(s) containing your user profile(s) from one machine to the other. On Win 10, user profiles should be located here:
C:\Users\[User]\AppData\Roaming\QGIS\QGIS3\profiles\. If you don't find it there or if you use other operating systems, you can find the folder using
Menu Settings / User Profiles / Open Active Profile Folder or see here.
Copy the whole folders of the user profile(s) you want to transfer and paste it to the QGIS Profile Folder on the new machine. You can copy/paste several user profiles to have them at hand on all machines.
Menu Settings > User Profile you see at least one user profile
default and maybe some more if you created other user profiles. If you select a user profile, a new QGIS window with this profile opens - an QGIS will start with the profile you selected from now on when you start QGIS.
It's quite handy to have different user profiles for different tasks - different GUI language, one with and one without installed plugins etc. For more details see documentation.