If I was in Malaysia, I would have spent just one day in KL and visited Batu Caves, Petronas Tower Observation Deck and KL Tower. For rest of the days I would have headed to Sipadan for some diving and chilling at the Beach. But if you want to spend more days in KL you may refer the below link: https://jetsettingfools.com/kuala-lumpur-itinerary/
Do batu caves murugan temple, Visit the Petronas and KL Tower, China town, and visit loads of malls across the city. I personally liked Berjaya Times square