"Fixes a limit" is a phrase that implies setting boundaries or constraints on a particular situation. There are several synonyms that can be used in its place, such as "establishes a boundary," "determines a maximum," or "sets a cap." These phrases all convey the same idea of creating limits or restrictions. Another synonym for "fixes a limit" could be "imposes a restriction," which implies a more active role in enforcing boundaries. Whichever phrase is used, it is important to clearly communicate the idea of creating limits or boundaries to avoid misunderstandings or confusion.