Is it possible to force a network to use a remote proxy server?

[void]

having the LAN users directly connect to the internet, i would like to force the users of the LAN2 and the WLAN network to transparently use my providers proxy server. the server is a squid socks proxy running on proxy.example.com:1080.

this should be transparent, so the LAN2 and WLAN user doesn't have to setup a proxy server in their browser.

do i need to use pfsense's squid proxy package for that?

the closerst thing i found was:
https://www.neowin.net/forum/topic/1047477-redirecting-squid-transparent-proxy-through-vpn/
https://forum.pfsense.org/index.php?topic=32732.0

piping the traffic through vpn would also be interesting.

my question on serverfault (i should stop asking questions there…):
https://serverfault.com/questions/847127/how-to-force-some-wlan-users-to-transparently-use-a-remote-proxy-to-access-the-i