Looking for advice on creating some type of router to wireless modem system

I used to run a computer business but have been out of the craft for several years, plus we didn’t deal with more than one wireless router at a time. I now live in a 2 story home with all my computers being upstairs in my bonus room, but not all of them have wireless capability. Rather than pulling cards out of the desktops to make room for a wireless card, I am asking you here for advice. What I would like to do is to setup my additional wireless router as some type of access point, bridge or extension and be able to connect the PCs CAt6 cables to it. I don’t know if it can be done but if it can, without physically connecting the wireless to the modem, which has wireless built-in. If anyone has an answer or suggestion, I will be grateful
Wireless