How to sync yahoo notes on iPhone to notes on ipad.
How to sync iPhone yahoo notes to ipad notes
iPad Air, iPadOS 15
Assuming that you have already added your Yahoo Mail account to both devices, you should be able to enable synchronisation of Yahoo notes via your Mail settings:
Settings > Mail > Accounts > [Your Yahoo Mail account] > Notes - set to ON
Check that you have set Notes to ON for both iPad and iPhone.