Its disabled on all most switches by default not just 9ks , 3ks and 4ks are the same , its protecting the switch you dont need it to troubleshoot layer 2 macs , you just use the command show mac address-table to see the full mac add table or show mac address-table address H.H.H
if you want to turn it on its per specific vlan --- mac address-table learning ?
vlan MAC Address table learning per VLAN
You could cause issues disabling it , its not really recommended
Disabling MAC Address Learning on an Interface or VLAN
By default, MAC address learning is enabled on all interfaces and VLANs on the router. You can control MAC address learning on an interface or VLAN to manage the available MAC address table space by controlling which interfaces or VLANs can learn MAC addresses. Before you disable MAC address learning, be sure that you are familiar with the network topology and the router system configuration. Disabling MAC address learning on an interface or VLAN could cause flooding in the network.
For the specific doc for your software release will be its config guide, there is a link to it where you download the image on the Cisco website , like example below
https://www.cisco.com/c/en/us/support/switches/catalyst-9200-r-series-switches/products-installation-and-configuration-guides-list.html
