LiquidText is a great iPad app you can use to annotate your PDFs, gather and organize your information across all your documents and webpages. You can create your own workspace in LiquidText and start importing your documents from popular cloud storage platforms such as Dropbox, iCloud Drive, Box, or email. And if you use Safari, you can send web content directly to workspace.
https://www.educatorstechnology.com/2019/08/a-good-pdf-annotating-app-for-teachers.html