When my arms hang down to my sides i feel like the veins get bigger and i can feel more pressure is this normal?

Multiple reasons: Veins return blood back to the heart and can carry a large volume of blood. Depending on many factors including levels of hydration, genetics, outside temperature and even physical activity, the size of the veins will vary. Another important function of the veins is to help control body temperature and this too will affect vein size. Also with aging, veins enlarge as tissue volume decreases.

Yes: When your arms hang down the blood must return to your heart by veins-in most people this can be several feet and creates a pressure gradient. When you raise them over your head the reverse is true and the veins collapse and become less prominent. So yes, this is normal.