As in any other field, you are not obliged to work there for some time. Of course, when you have a contract, you must respect it, but all contracts have different clauses that are mentioned where you can see what happens when you want to give up your job. You need to understand that no one will keep you there against your will. You can quit even after a few months if you do not feel like this job is for you and want to reconsider your decision.