Have you ever wondered about this verse in Jeremiah? Here's one perspective:
What Does It Mean That God Knows the Plans He Has for Us?
In the context of Jeremiah 29, the phrase, “I know the plans I have for you,” refers to the plans the Lord has had for the people of Israel from the beginning. This verse is a reiteration of the promises of God, as well as the guarantee that He always keeps His covenants.
https://www.crosswalk.com/faith/bible-study/the-beautiful-context-of-jeremiah-29-11-for-i-know-the-plans-i-have-for-you.html?