Too much work.Independently if your playing on console or PC you can add artificial lag by saturating your LAN downloading some heavy stuff in this or other device connected to the same LAN.
Example: someone else starts to watch 4K video streaming, some OS/firmware/driver update downloads automatically, etc.
Extra lag also happen -both for console and PC- for simply being too far from the other player, playing via wifi, specially if with bad wifi signal or being too far from the router, old wifi type, bad router/firewall/etc. configuration, having a shitty quality internet connection line, or if using some weird internet connection like 4G/5G/satellite that in addition to extra lag loses many packages, or because the info packages found an "internet traffic jam" when travelling from a player to another.
I'm sure there is a easy way to create artificial lag in PC.
I mean...