I doubt there’s an FBI agent there, even in a consulting role.
We have Texas Rangers, and they remember the last time the FBI came to Texas and got involved in what was really a local problem. The FBI and the rest of the Feds blew it and dumped the disaster on the Rangers once it was over.
The FBI remembers the damning report the Rangers produced when they dumped the Waco remains on them. They expected the locals to “clean up their mess”. Instead, the Rangers treated it as a crime scene, did a thorough and professional forensic investigation, and produced a report that slammed the Feds for (among other things) lack of professionalism and triggerhappiness. Surprise! There *are* better law enforcement organizations than the FBI, and the FBI just tried screwing with one of them.
The FBI is going to want to be far, far, far away from this.
That said, what probably happened was that either that team is a Ranger team, or there’s a Ranger on point with the warrant.
Even if the FBI didn’t want this case, there is the possibility of kidnapping, and that is a federal crime. They will have someone there observing, and will step in if they have to, even if if it reluctantly. They probably won’t have to, which is just fine because the Rangers can handle this without their help.