@SteveITS Hi Steve, the log is showing below.
It seems that it is using that by default.
Oct 14 19:40:17 kea-dhcp4 25524 WARN [kea-dhcp4.dhcp4.0x2fcfd0e12000] DHCP4_MULTI_THREADING_INFO enabled: yes, number of threads: 4, queue size: 64
I can modify it, per the below
sed -i '/"Dhcp4": {/a\ "multi-threading": { "enable-multi-threading": true, "thread-pool-size": 2, "packet-queue-size": 64 },' /usr/local/etc/kea/kea-dhcp4.conf
But I want to do it in a way that is persistent through upgrades