For comfort you do not want to be looking substantially upward or tilting your head back. It’s much better for your eyes to put the display lower and look down (by swiveling your eyes, not your whole head) for the bottom part instead.
For typing it works well with a large display to put the bottom of the display barely above the desk, push it back as far as you can (constrained by your workspace) and tilt it backwards near the top, and position the desk/chair so that the desktop is at roughly waist height (let your upper arms dangle loosely at your sides with your elbows close to the body and bent about 90°, keep your wrists straight, and position your fingertips at the tops of the keys of a keyboard resting on the desk).
I have a 27" display ("5K") and the top ends up just slightly below eye level. If you have a 40" display or something the top will probably end up a bit above eye level.
Your eyes need to focus and converge on the display surface irrespective of the distance or orientation of the display and irrespective of the font size.
But as a general rule, the further the display surface the less your eye muscles need to work. So if you can put your display 3m away from your eyes that is better than putting it 30cm away.
On my desk, about 90cm from my face is the furthest I can manage, but if you have more space in your work room, by all means put the display significantly further than that.
For typing it works well with a large display to put the bottom of the display barely above the desk, push it back as far as you can (constrained by your workspace) and tilt it backwards near the top, and position the desk/chair so that the desktop is at roughly waist height (let your upper arms dangle loosely at your sides with your elbows close to the body and bent about 90°, keep your wrists straight, and position your fingertips at the tops of the keys of a keyboard resting on the desk).
I have a 27" display ("5K") and the top ends up just slightly below eye level. If you have a 40" display or something the top will probably end up a bit above eye level.