by 'text/edit' I'm assuming you mean TextEdit
First, if it's not already set to page layout 'Wrap to Page', then Cmd ⌘ Shift ⇧ W to activate that, then you can see how it will flow to a printed page.
Select all text with Cmd ⌘ A then
Cmd ⌘ - to reduce overall font size or
Cmd ⌘ + to increase.
This will only affect text, not any embedded pictures. They would need to be edited separately in an external photo editor.