Help me understand this OLX scam possibly

I was looking for iPhone 16 Plus on OLX and this person showed near me, but now they are saying that they are shipping from Jalandhar side or something and they are selling iPhone 16+4 30,000 and they are doing it on COD, so I don’t know. I just have to pay them shipping charges of 300 and I can just get the delivery of shipping. Yeah, that’s it. They have showed me the phone and everything seems fine I don’t know. I know there is a scam here, but I don’t know what?