grandiose

impressive because of unnecessary largeness or grandeur; used to show disapproval

Impressive or elevating in effect; vimposing; splendid; striking; -- in a good sense.

Latin grandis (large) + -iose (making...)

“She really had the heroical aspect in a grandiose-grotesque, fitted to some lines of Ariosto.”

— George Meredith, Complete Project Gutenberg Works of George Meredith

“They may feel unstoppable, persecuted, or as if they have a special relationship with God, a great mission to accomplish, or other grandiose or delusional ideas.”