Your search term would be "wiring harness manufacturer". I've not come across anyone in this space that would take a web order like PCB fabricators unfortunately, the demand isn't there.

If you need wiring harnesses or other cable assemblies you'd usually make them yourself, buy a COTS cable that is close enough and make your design match that or bite the bullet and go to a fabricator and pay expensive Non Recurring Engineering (NRE) costs. Anyone good will have an IPC-A-620 certificate.

Unless you're Toyota, its probably worth buying your own set of crimp tools rather than going down this route. WireViz is a great tool for documenting cables for your own purposes, but is only part of what would make up a full drawing pack for a wire harness.