Magniloquent describes a style of speaking—a tone and style like that of a king giving a public speech, a style of exaggerated importance and formality.
Munificent describes a person, a gift, or a behavior which is generous or kind.
Magniloquent is formed from magni- meaning “great” and -loquent which means “speaking.” Another word with similar roots and the same meaning is grandiloquent, a word often used instead of magniloquent. Magniloquent is archaic and unlikely to be heard outside of old literature, so you should probably use grandiloquent instead:
The speaker’s grandiloquent style of speaking made him seem egotistical.
Munificent is also a high-style word, not conversational, but not uncommon