When I try to add UI text it appears to be very large and located somewhere far away from my objects.

Something like this

that’s because you set the Canvas as ScreenSpace - overlay.

ScreenSpace - overlay appeared as a really big objects in the scene view, and intended to be used as separated UI from the world view

if you want the canvas to be as big as the camera in scene view, simply change it to ScreenSpace - Camera or WorldCanvas and set the mainCamera as the Render Camera