That's easy enough to simulate on Linux if you want to try. Replace eth0 with your wan interface. Re-paste the "del" lines to clear the added latency. If testing this on a remote host I would suggest adding a cron job to run the "del" lines every 10 minutes. I am typing this from memory so it may not work quite right. Use "tc -s -p qdisc" to get the packet statistics. All of these commands need to be run as root or with sudo.
# outbound qdisc
tc qdisc del dev eth0 root > /dev/null 2>&1
tc qdisc del dev eth0 ingress > /dev/null 2>&1
tc qdisc add dev eth0 root netem delay 250ms 20ms
# inbound qdisc
modprobe ifb numifbs=1 && ip link set dev ifb0 up
tc qdisc del dev ifb0 root > /dev/null 2>&1
tc qdisc del dev ifb0 ingress > /dev/null 2>&1
tc qdisc add dev ifb0 root netem delay 250ms 20ms
250ms 20ms means add a latency of 250ms with a variability of 20ms. This test will break at some point but one could test the impact of this using a speed test [1][2]
[1] - https://www.dslreports.com/speedtest#
[2] - https://fast.com/