The problem with real world Chi is that it is actually a conflation of various unrelated concepts.
In medicine context, Chi might refer to the nervous, circulatory, or endocrine system.
In martial arts context, Chi can refer to manipulation of one's own or the opponent's center of gravity, or to the use of psychological intimidation, or to make use of reflexes to force predictable response. Any martial artists would tell you how important it is to maintain a sense of balance to avoid being thrown, how to shift balance to prepare for certain moves, or how to manipulate opponent's center of gravity to take people down with less than brute force. A street brawler would tell you how they would intimidate their opponent to make them hesitate during critical moments of an attack. A martial artist may also tell you how an attack to the face would cause most (untrained) people to reflexively try to protect their vitals (eyes) in fairly predictable ways which is used to lead for the follow up attack. Of course all of these are commonly over exaggerated in tales and frauds to unrealistic extents.
Essentially, ancient eastern culture uses Chi in similar way that ancient western culture uses God to explain away any unexplained natural phenomenons or disasters on which people know it happens, but don't know why or how it works. A close scientific scrutiny would show how these previous explanations are unsatisfactory.
If you want to include elemental manipulations, you necessarily have to either invent new forces that we don't have in our world (e.g. some sort of magical ether) or allow the use of external tools (e.g. using low ignition oil/gunpowder to make fire, throwing sand to blind an opponent, sleight of hands, etc). You would also necessarily have to include low scientific literacy, such that most of the world's inhabitants are ignorant of how the physics in their world works.