You can enable File Sharing immediately, without adding any other software.
System preferences > Sharing > File Sharing
Now about the SPEED of file transfers...
Modern Macs can do Gigabit Ethernet with jumbo frames, but most more-mundane equipment (like Routers) do not support jumbo frames. You may need a Gigabit Ethernet Switch, and put your regular Router on a spur (off the Switch) going to the Internet. Devices on your local Subnet transfer packets directly, without requiring the "Router" portion of your Internet Router to be used (they only use the "Switch" [store and forward] capability).
If you want more advanced features, you could install MacOS Server, but it has a steep learning curve and more and more of its fancy features are already available in regular MacOS.