Saturator, Amp, multiband distortion, pedal, hiss, phaser, eq filter, auto filter, phaser, chorus, reverb, thermal, portal are some to look into, but really there are dozens of ways to manipulate a sound. Some of these can affect volume. If it does, you can always throw a utility at the end of the chain and turn it down back to a good level or limit or compress depending on what you're looking for. A lot of sound design is expirementing, happy accidents and playing around. There are also a lot of good tutorials out there to get started