remember:

eth0 - this is my network interface, change it if needed

1. Add this lines in wg0.conf:

[Interface]
PostUp = iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

or run one the command for testing purposes like this one below

iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

2. Modify clients WG config in this way (adjust to your needs if necessary):

[Peer]
AllowedIPs = 192.168.99.0/24, 192.168.30.0/24

3. Enable net.ipv4.ip_forward = 1 on WG server.

how to edit:

1. type "nano /etc/sysctl.conf"
2. find #net.ipv4.ip_forward=1 and change it to net.ipv4.ip_forward=1 removing # character
3. reload sysctl using "sysctl -p" command