Boundaries can be used in multiple diffrent ways. In different interpersonal systems ranging from one’s significant other to a supervisor or co-worker. Boundaries can be also used in different situations, emotionally, physically, and even within one’s self. Though boundaries are usually seen as something between one person to another it is important to note that they can also be used internally to set boundaries within.
Psych Central has an article entitled “10 Ways to Build and Preserve Better Boundaries” This article highlights multiple ways to create these boundaries and how to keep them stable.
https://psychcentral.com/lib/10-way-to-build-and-preserve-better-boundaries#1