"Make yourself at home" is a phrase used to make someone feel comfortable in a new environment. There are several synonyms for this phrase that can be used in different situations. For instance, "feel free to relax" is a simple way of expressing the same sentiment. "Make yourself comfortable" is also a common phrase that can be used to offer a person the same invitation. Another possible synonym is "settle in" or "get comfortable," which may be appropriate in more formal settings. Overall, these phrases are used to signal to a newcomer that they are welcome, and that they should feel free to relax and make themselves comfortable, as if they were in their own home.