systemctl start service-{a,b}.service would be equivalent to systemctl start service-a.service service-b.service
systemctl start srv-{1..4}.service would be equivalent to systemctl start srv-1.service srv-2.service srv-3.service srv-4.service
If for example you had multiple wireguard services and wanted to enable both the service and path for each
systemctl enable wg{0..3}.{service,path} would be equivalent to systemctl enable wg0.service wg0.path wg1.service etc...
this trick only works when you can chain multiple arguments one after the other
I have tested the above with both bash and zsh
zsh extends this by allowing the following:
for ip in 192.168.0.{1..254}; curl $ip -I as a crude web server scanner