Remember that pounds is a unit of force - not mass.

There's the set of "tech neck" images (example https://www.vital-balance.com/en/tech-neck/ though many more can be found) where it shows what the force on the neck is from the head. At 0°, it's 10-12 lbs of force down. If you've got your head tilted at 45° looking at a phone, the infographic says that its 49 lbs of force on the neck.