OOTB for Physical Products and other object types the default counter is 8-digit.

https://help.3ds.com/2021x/english/dsdoc/spacecontrolmap/exp3dbasicsadmin-c-content-identification.htm?contextscope=onpremise

• is a 8-digit number automatically-generated by the server, a separate counter is used for each type of content

Granted it could take a while, but on-cloud or on-premise, if the counter is at 99999999 will the next creation trigger an error of some kind or by default just up the counter to 9-digit (i.e. 100000000)?