In Yahoo Mail, I can add my Gmail account using Settings -> Manage Accounts, so that I can send and receive Gmail messages from within Yahoo Mail.
How can I configure Outlook.com with my Gmail account to do the same thing?
You used to be able to, however Microsoft removed the ability to add them from Outlook.com in 2021. Any external accounts added before that date still worked until Microsoft completely disabled the feature in 2024.
If you pay for a subscription to Microsoft 365 Basic, Personal or Family, you can add external accounts.
Microsoft now suggests that Outlook.com users either:
Forward external account messages to Outlook.com
Access external accounts using one of Microsoft's standalone apps: