Because you are using POP, which removes emails from the server once they are downloaded, this is going to get very messy.

Before you start - Make a backup of the original PST you brought over from your old PC and put it someplace outside the normal Outlook directories. e.g. "C:\OlkBackup".

Create a new, no email Profile. Name it something like "Consolidated". Change your settings to "Prompt for a profile to be used".
How to use Outlook 2016, 2019, 2021, and Office 365 without an associated Email Account - CompanionLink Support

In Outlook, using the Consolidated Profile, start adding your POP accounts. During setup for all of them, tell it to use the same, original PST you brought over from the old PC. Follow these instructions. NOTE - If it doesn't let you get to the "Advanced Setup" screen and tries to setup the account automatically you will have to use the "Invalid Password" trick.
Manually add POP or IMAP accounts to Outlook | Slipstick Systems

Once you get all the POP accounts setup in the Consolidate Profile - Import the emails from each of the separate PSTs that were created during your first try. Be sure to NOT import duplicates.
Import email, contacts, and calendar from an Outlook .pst file - Microsoft Support