You probably need to check with your ISP. I believe fiber has some type of device outside the house which converts it to what you need.
You may be able to get some info by just searching the Web for fiber installs.
You don't mention the speed of the new connection. If it is higher than 1 Gbs, there is some doubt if the 2.5 Gbs LAN port can do a WAN speed of higher than 1 Gbs. You might be able to answer that question.
Maximus Z790 Hero,
Intel i9-13900k
Intel BE200