Yes and no, the answer really depends on the class. There are plenty of opportunities to work as a portrait model, where you would not be nude. In these classes the model usually has to hold the same pose for an extended period of time, the frequency and number of breaks depend on the group.
However, modeling for figure drawing classes pays better than portrait classes and you would have more opportunities for work as a figure model. It is a requirement that the model is completely nude for a figure drawing class. There are some cases where the model will be “draped” in some poses but that varies from group to group.
Depending on who you ask, being nude can either be “the worst part of the job” or “the most liberating part of the job.” Generally speaking, if you are weighing whether or not to do nude modeling based on how much it pays, you’re really not interested in doing it.