Separating networks

Hello noob is here and i will be fast, i saw this topic alot but i think i have a “different” problem…
In my case i took the cable from the lan port of the router that ISP gave me and plug it in the mikrotik router…All i want is to separate that line with a mikrotik router. Is it even possible or i should replace ISP router with mikrotik and create vlans?
If it is possible like i imagine what should i do…

ISP Device: Is it a modem/router or just router? Does it provide TV or telephone services or just internet?

Just a coax from the isp is pluged in and 4 lans are used for home network, i want my line (lan that im using) to separte from the others

So just internet COAX cable to ISP modem router and you get private IP from ISP modem router LAN.

Just plug one cable into your MIKROTIK ROUTER and then all users plugged into mikrotik router.
One bridge, create as many different vlans as you need to separate users, servers, iot equipment etc.