If I lift my truck do I need to lift my suspension also?

uh yeah

A body lift utilizes blocks and spacers to lift the body higher onto the frame of the vehicle without altering any of the suspension geometry. With a body lift kit, your ground clearance remains unchanged, but the extra height allows you to run larger wheels and tires. The steering geometry remains unaltered as well, so your rig retains most of its original driving and handling characteristics. Stability can be negatively impacted, though, due to the increased ride height. Body lifts tend to be more affordable and easier to install than their counterparts – suspension lift kits. Although limited in the amount of lift they can provide, body lift kits offer that lifted look, accept larger off-road tires, and have less effect on the drivability and comfort of your ride.

A suspension lift creates additional clearance by spacing the factory suspension or by replacing the entire suspension with components designed to raise the chassis. This can be done by using taller coil springs, coil spring spacers, torsion bars or keys, lift blocks, shackles, or add-a-leafs. Depending on kit, you’ll often get new shocks, bushings, and meatier control arms as well.

Source : https://techprotools.blogspot.com/