NB! It seems this console command is not compatible with CS2.
Command Profile

NET_FAKELAG

CS:GO

This command will simulate lag (high latency/packet delay) for the specified amount of milliseconds.

Syntax
net_fakelag [Milliseconds]

Description

This command will simulate lag (high latency/packet delay) for the specified amount of milliseconds.

Syntax And Arguments

net_fakelag [Milliseconds]
Milliseconds The amount of milliseconds to fake lag for. 2000 = 2 seconds.