The phrase "boxes in" can be used to describe something that is enclosed, confined, or enclosed in a limited space. There are several synonyms that can be used to convey the same meaning, such as "encircle," "enclose," "encompass," "surround," "hem in," "trap," "corner," "constrain," "restrain," and "restrict." All of these words can be used to describe something that is limited in its movement or ability to escape. Whether it's a physical object or a person's freedom of movement, using these synonyms can add depth and variety to your writing.