the way to write real-feeling dialogue is to just start writing with no real plan and let your characters talk to each other.
bear in mind the plot that you want to achieve and whatever, sure, but don't plan out all aspects of a conversation.

if you feel a bit confused about something that a character says and think it could do with clarification, don't re-write it to be super wordy or exposition-y - have another character ask what they mean.

also, write "um"s and "uh"s into your dialogue if you find yourself pausing to figure out how to continue a sentence. characters in fiction ever seem to um and uh anywhere NEAR as much as people IRL do and i think that's a shame, it makes dialogue feel natural and comfortable.

i'm COMPLETELY unqualified to be saying this btw. it's just that natural-feeling dialogue is the only thing i've ever been properly good at when it comes to writing.
so like if you wanna share tips about anything other than this in this thread i sure would be grateful!!