See the article Manage your iCloud storage - Apple Support
As per the article Create notes on iCloud.com - Apple Support
To attach items to notes, use the Notes app on your iPhone, iPad, iPod touch, or Mac that is signed in with the same Apple ID. You can view or download those attachments in Notes on iCloud.com.
After you create or edit notes on iCloud.com, your changes appear automatically in Notes on your devices that are signed in with the same Apple ID. If you’re using upgraded notes, your changes appear on your devices with upgraded notes that are signed in with the same Apple ID.
Read Share your notes on your iPhone, iPad, or iPod touch - Apple Support