For the feature seen in the following documentation:

https://www.juniper.net/documentation/us/en/software/junos/multicast-l2/topics/task/layer-2-services-lldp-configuring.html

chassis-id-type (chassis-component | interface-alias | interface-name | locally-assigned | mac-address | network-address | port-component);
chassis-id-value chassis-id-value;

• chassis-id-type—The default value is MAC address.
• chassis-id-value—The default value is system-mac.

CLI not showing the option to modify this.

 Regarding this CLI command, it was introduced very recently in 23.4R1.

Versions prior to this one will not display this option.

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/protocols-lldp-chassis-id.html