In a user's Calling setting, you can configure which other lines should be monitored by the user. Those will show up in the monitored line spots on the phone/kem. In the device settings, you may also configure how the lines should be presented, ie. only name or name/number etc.
AFAIR, these layouts are individual to the user, so you cannot create templates to copy them to user users.
At least, you may use the API to bulk edit (copy/paste) monitored line settings for users: https://developer.webex.com/docs/api/v1/webex-calling-person-settings/modify-a-person's-monitoring-settings