I believe some (most?) routers can be made to act as a "wired" extender/repeater by plugging its WAN port into the main router (e.g., via PowerLine adapter), changing it's internal IP address to something other than the main router's IP address (e.g. 198.168.1.2 instead of 198.168.1.1), making its wireless SSID unique, and turning off DHCP (so that devices connecting to it use the main router's DHCP service to obtain their IP address).
If you want a "wireless" repeater/extender that connects wirelessly to the main router and devices connect via wire and/or wirelesslessly to it, you need to look for that specific feature.