I have found tools like Smart Ruler that helps us measure length using the screen. But for objects bigger than the screen, I imagine there are apps that use the camera and focal length to show distances and widths. If there's no such app, is it possible to use a camera or any other common phone hardware to measure spatial dimensions?
I just found an app from the same developer that does what I wanted for buildings: Smart Measure.
This rangefinder (telemeter) measures the distance and height of a target using trigonometry.