When citizens get involved in the political process by joining volunteer organizations, are they engaging in a social contract?

That statement is false

Explanation:

Social contract refers to the agreement between the citizens and the government, in which the citizens agreed to sacrifice a certain portion of our freedom to the government in exchange of their protection and social stability.

Example of social contracts usually connected to us submitting to the government's authority (such as paying taxes, following traffic lights , etc)]

When we are willingly   Volunteer to a certain group, it does not considered as engaging in social contract.

the structure of state governments are determined by. "state constitutins'

under the us constitution, all state governments are.'republics'