Yes, you can sync notes between those devices by using iCloud and GoodNotes.
Here's how to set up iCloud:
1. Open the Settings app on your main device (ie. iPad)
2. Tap your name to open the Apple ID screen
3. Select iCloud.
4. Turn on the toggle switches next to every category of app and content that you want to sync between the iPhone and iPad.
5. Repeat this process with the second device.