There are certainly instances where we're told the Lord changed his mind. Usually for the good of those who plead for mercy.
Now, is someone going to suggest that: (1) The Lord determined the Trump would be inaugurated on Jan 20, 2021, (2) told his prophets to spread the word, then (3) changed his mind?
There are several places where God changes His mind; He offers humanity a choice several times. One poignant event was where He told Moses that He would destroy all of the Israelites for the sin of the golden calf and instead make Moses the new patriarch of “a great nation” (Exodus 32:10). Moses prayed to God directly to spare Israel in verses 11, 12 and 13, with verse 14 making it plain that God accepted Moses’ entreaties.
I don’t recall hearing/reading any specific prophecies that Trump would be inaugurated on January 20, 2021; I’m sure some are out there notwithstanding, and those are obviously false.