As a general rule, no. The purpose of DUI checkpoints is to stop the danger of individuals driving while under the influence. That is why courts have made an exception to the rule that probable cause is needed to pull over motorists for probable cause — because of the danger of drivers under the influence.
However, once law enforcement has stopped a vehicle, if they observe something in plain sight, they may make an arrest or seize an item. For example, if a passenger has illegal drugs on their lap at a DUI checkpoint and the officer can see those drugs (and their illegal nature), then the passenger may be arrested for drug possession.
