I have to switch off two-factor authentication in order to setup my Icloud account to Outlook

Two-factor authentication is enabled by default on new Apple IDs and cannot be turned off.

If you have an old account and recently activated Two Factor Authentication note this section of an Apple support article:

"Two-factor authentication for Apple ID" - https://support.apple.com/HT204915

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"Can I turn off two-factor authentication after I’ve turned it on?

... If you recently updated your account, you can unenroll within two weeks of enrollment. Just open your enrollment confirmation email and click the link to return to your previous security settings ..." Updated December 08, 2020

From: Mail server settings for iCloud email clients - Apple Support

Use iCloud for Windows on your PC in Microsoft Windows with Outlook 2010 through Outlook 2016. Set up two-factor authentication and, if needed, generate an app-specific password* to use for iCloud Mail.