full of oneself
Conceited, self-centered, as in Ever since she won the prize Mary's been so full of herself that no one wants to talk to her. This expression uses full of in the sense of “engrossed with” or “absorbed with,” a usage dating from about 1600.
From POTUS To FLOTUS: A Full (White) House Of AcronymsThe faster we move, the more abbreviations and assorted acronyms we use, and when it comes to talking about the folks who reside at 1600 Pennsylvania Avenue—otherwise known as the White House—there are plenty of acronyms to choose from.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.