If a modem is connected to a router by ethernet and that routers Ethernet ports are 10/100Mbps is the Maximum speed of that routers WiFi going to be 100Mbps?

To be more precise, a friend has his eye on a 3 node mesh Wi-Fi network. The Ethernet ports on the bottom of what will be is primary node is only 10/100Mbps. However, his ISP is feeding his modem a 200Mbps line, and his modem has 10/100/1000 Ethernet ports.

Will his WiFi speeds be limited to 100Mbps ?