Yes, it's possible to change. By default LDAP users will be imported based on their 'CN' attribute, which is usually the same as 'DisplayName'.
You will need to change the CNID value under your LDAP profile to change the behavior.
For instance, if you want your users to be imported with usernames based on the 'userPrincipalName' attribute, use the bellow configuration:
config user ldap edit "YOUR-LDAP-PROFILE-NAME" set cnid "userPrincipalName" next end
If you want the imported usernames be based on the 'sAMAccountName', simply change the settings as bellow:
config user ldap edit "YOUR-LDAP-PROFILE-NAME" set cnid "sAMAccountName" next end
Just note that after you change the value, you will need to delete and re-import all users again.