To format the text there is Aa, at the top right, as on the Mac; with the screen’s keyboard also above the keys, next to Bold and Italic. The same commands, with Review, are in the menu that appears when you select text and in the menu bar, under Markup, with the Mac’s shortcuts.
Links, footnotes and comments sit in the text as small signs: ↗, ¹, ✳. Tap a sign to read or change it.
With Apple Pencil, Scribble turns handwriting into text where you touch. Find and Replace in the document is in the selection menu, or ⌘F; Search in Project, at the top of the sidebar (⇧⌘F), searches every document and replaces.
Review is the Mac’s. With Track Changes While Writing (⌃⌘R) what you write becomes a suggestion and what you delete stays in the text, marked to be removed; Tracked Changes at the bottom of the page says so. Touch a suggestion: Accept and Reject are the first commands of the menu. Accept All in Document and Reject All in Document are in Review; in the inspector, the Review tab lists them all.
Image, in Aa or in the Markup menu, takes a picture from the Photo Library… or from Files…; you can also drag it onto the page from another app. Finis copies it into Media and shows its thumbnail on the page: a tap enlarges it. Another file dragged onto the page becomes a link; dragged into the sidebar, it joins the project.