Can’t edit pdf on iPhone 8

Trying to edit a "binder" I put together of 21 pages. I need to insert additional pages to make sure the correct pages are front and back while the single sided pages remain as such. But my phone for some reason will only allow me to highlight, comment, draw, strikethrough or underline the text. It will not allow me to insert a page. I can't even find the edit pdf option anywhere. Please help me