Toyota does not do custom builds. Ever.
Dealers are allocated vehicles that Toyota sales puts together. Dealers can put requests in to change some thingd, sometimes, like paint, or port options, but bulk stays the same. Sometimes dealers will trade allocations before truck is build, to get what their customer wants.
Most "custom" options these days are whether you want the $400 Toyota all weather floor mats, or the blacked out badges. I talked to a dealer and built out a Tacoma the way that I want it, which is a Manual, double cab, 4×4 Off-road version with a couple of options and I was quoted $41,××× OTD. Used ones are more than that now.