Is there such a field (concept) of transport mode in NetSuite (ie. ocean, air, rail, truck, etc)? (I've seen this, but its of no user ... https://docs.oracle.com/en/cloud/saas/netsuite/ns-online-help/section_1505110665.html)

not that I'm aware of. some companies use shipping methods if they are not also integrated to UPS/Fedex