Older emails didn’t transfer from my old iPad to my new one.

On your new ipad, go to Settings > scroll down to Passwords and Accounts > under Accounts on the right side, select your email account, when it opens, you should see “Mail Days to Sync”, select your choice. I hope this will be of help to you.

Email isn’t transferred between devices during device setup - but email account settings should be. Your email content can be downloaded again from your email provider’s Mail server.

The Mail Days to Sync item is specific to Microsoft Outlook accounts. This configuration item may not be natively available for other Mail providers.