Justin Ludwig has written a bunch of very good wireguard tutorials for the Pro Custodibus (wireguard management software) blog; can learn a lot about networking in general from them. A few I found useful:

WireGuard Endpoints and IP Addresses
https://www.procustodibus.com/blog/2021/01/wireguard-endpoints-and-ip-addresses/

WireGuard Hub and Spoke Configuration
https://www.procustodibus.com/blog/2020/11/wireguard-hub-and-spoke-config/#configure-wireguard-on-host-c

WireGuard Access Control With Iptables (There are also articles for ufw and nftables)
https://www.procustodibus.com/blog/2021/04/wireguard-access-control-with-iptables/