If you dont have an additional rmm tool or something to manage the device ,it would be up to the end user to manually enroll the device.
https://video2.skills-academy.com/en-us/mem/intune/user-help/enroll-windows-10-device
But... "personal computer" please beware of what you are getting yourself into! Maybe a better idea would be to use MAM for windows (edge) to access company resources from those devices or give those users a cloud PC.
But restricting their personal devices... i wouldn't be okay with that if it was my own device ... let alone think of what happens when somehow the device gets bitlocker encrypted, reboots ask for the recovery key but somehow that key isn't uploaded to azure... guess who they will blame :) ... not me :P