Adding a new iCloud email
I would like to add a new iCloud email to my existing emails
You can create a new iCloud Apple ID say example1@icloud.com from web see the article How to create a new Apple ID - Apple Support
That can be added in internet accounts from Mac .
See the articles Use your Internet accounts on Mac - Apple SupportUse your Internet accounts on Mac – Apple Support (AU)
Add an internet account - Apple Supportsupport.apple.com › guide › mac-help › mac
This iCloud mail account will be added to your existing mail accounts in apple mail application .