I grew up near there, but I don't recall anyplace I'd call a "downtown." It's a suburb of K.C.
Downtown Overland Park is the old downtown. It's West of Metcalf and about 79th street. It's been thriving lately with a wonderful farmer's market, specialty shops, lots of art galleries, coffee shops, antiques. This is devastating.
"Downtown" OP starts at about 79th St, from Metcalf to the west. Santa Fe Trail Dr. runs thru there.