I just bought my 2016 Sierra 1500 Elevation with 124k on it, good deal with trying to push cars off lot because of pandemic.
Minor problems, such as rear brake line needed to be replaced (stretched and snapped?) , AC condenser needed to be replaced (hit with a bird at some point), and needed a crank shaft position sensor replacement that the dealer replaced all before taking off the lot. Put 1000 miles on in the last 2 weeks and its been running great, I did get a 100k service contact and am somewhat mechanically inclined if there are problems later. All maintenance records point to last owner keeping up to date on recommended maintenance at GM intervals.