The attached gif explains what snownut2 is referring to. Put the text in paperspace and work on your model through an unlocked viewport.
I do understand paperspace will make the sizes fixed. But like I have explained, this is not what I wanted to do. Take
Grrr1337's gif as an example, I want the line object information to be displayed at the middle point of each line. Whenever I move/rotate the view port, the object information text will follow the line objects instead of having fixed locations. it is basically like normal texts, but they are always facing the screen with a fixed sizes.