What are the additional security measures for Apple ID

See these security-related documents:.

If you think your Apple ID has been compromised https://support.apple.com/en-us/HT204145

Security and your Apple ID https://support.apple.com/en-us/HT201303

iCloud security overview  https://support.apple.com/en-us/HT202303

Ways to keep your information safe on Mac https://support.apple.com/en-gb/guide/mac-help/mh11402/mac

Using app-specific passwords https://support.apple.com/en-us/HT204397

Use Two-factor authentication for Apple ID https://support.apple.com/en-us/HT204915

2 Factor Authentication.

Read here -> Two-factor authentication for Apple ID - Apple Support