Creating multiple WLAN with one router and switch

This is a bit confusing, so I hope I can explain it.

I’m on a network that I am not an administrator for. I can connect via Ethernet or WiFi. What I want to do is create 2-3 additional WLANs from this main network.

What I was thinking is that I can use a switch to connect directly to the network, then use a router to create the multiple WLANs I need. I’m not sure the best way to do this though.

This might be a stupid question, but can I connect one router to one switch multiple times? My impression is that each port on a switch creates its own network.

My end goal would also to be able to control the signal strength of each WLAN individually. So if I have networkA, networkB, and networkC: I could specify that I want networkB to have a very low signal strength while maintains A and Cs signal strength.