The phrase "fence in" is often used to describe enclosing an area or preventing someone from leaving. However, there are several similar phrases that can be utilized to convey a similar meaning. For example, "box in" or "cage in" could be used to describe the act of enclosing an area. Additionally, "constrain" or "restrict" could be employed to describe preventing someone from leaving or limiting their movements. Other synonyms for "fence in" could include "encircle," "surround," or "hem in," which all imply a sense of boundaries or limitation. Choosing the right synonym can help to add nuance and depth to your writing, making it all the more engaging and impactful.