Can you lose your license for drinking, possessing or purchasing alcohol without being in your car?

Yes.  If you are under 21 and are cited for underage drinking, at a party or some other locations, the State of California has the right to suspend your license, even if you were nowhere near your car.  Any person aged 13 to 21 cited, even if not convicted, may have their license privileges delayed, restricted or suspended for up to one year for each offense involving possession, consumption, and purchase of alcohol.  [V.C. sec. 13202.5; B. & P.C. secs. 25658, 25662(a)].