The phrase "take up a new job" is commonly used to mean starting or accepting a new job or position.

To "take in" means to absorb or understand something, or to allow someone to stay in your home.

To "take to"  means to develop a liking for something or to begin doing something as a habit.

To "take on" means to accept a challenge or responsibility. While it can sometimes be used in the context of starting a job, "take up" is the more commonly used phrase for accepting a new job.