Auto-add email accounts across devices

Hello, SmiffyBarcelona.

Thank you for posting in Apple Support Communities. We understand that you’re wanting your iPad or iPhone to automatically add the email accounts that you’ve added to your Mac. While your iCloud Keychain can store your internet accounts and passwords, it won’t automatically add those accounts to your other devices when you add them to your Mac. You’ll need to add those with these instructions:

Add an email account to your iPhone, iPad, or iPod touch - Apple Support

This is a great resource for what you can expect from iCloud Keychain: 

Set up iCloud Keychain - Apple Support

And another that outlines processes that work seamlessly across your devices:

Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support

Warmest Regards.

SmiffyBarcelona,

Apple is always looking for ways to enhance their products. It may be worth filling our their feedback form with your idea:

Product Feedback - Apple

Cheers.