Can you build up a tolerance to cocaine?

Yes: Narcotics give "tolerance". That means that sooner or later to experience the same effect the dosis required is going to be higher.

Yes: The more Cocaine you use, the more Cocaine you want. In the course of a Cocaine binge, it takes more and more Cocaine to squeeze out less and less dopamine, the chemical responsible for Cocaine euphoria. Eventually, there is no Dopamine left, and the user has to wait several days before there is enough to get high again. It is a very compulsive and dangerous drug. If this is you, stop. Get help.