You want this big boi? well we need preperation in the base first, RESOURCES:

Alot of tranq darts with a longneck rifle, Some behemoth gateways and gates, Prime meat or eXtRoIdOnArY kibble, some knowlege on taming traps, and a bait unless you use yourself, AND OF COURSE the rex tek saddle or rex saddle.

And there you have it folks! A tamed rex for you to control.