Need to buy the right adapter for iMac to second monitor

Just got a new iMac (2019) and it doesn't have the mini display port in the back anymore, so I need to replace my adapter that I was using to hook up my second monitor to fit the new port. The only thing coming out of my second monitor is a DVI Video connection, so should I buy a USB-C to DVI Video adapter? I'm still confused about the difference between Thunderbolt and USB-C but there don't seem to be any Thunderbolt to DVI Video adapters. Just want to make sure I get the right thing. Thanks!