[EC900]

The rodent nest blockage is one of the simplest possibilities that has to be eliminated before going on to other culprits. Mechanically the only other way to increase engine heat fast is no fan belt, assuming yours isn’t loose and the correct pulley and shims are used, including that the engine tins and side covers are in place too.

Also - Get an infrared thermometer gun and Temp check at the sender unit after you take another drive and see if gauge is accurate. Pull the gauge and clean the terminals and the Ground.

Borescope inspection camera will help and always a good tool just to have anyway.
It will make looking under the fan shroud easy, but also you can remove the small tin shroud cover plate on the right side. Looking thru the blades, you’ll only see one side and quarter way in.
Shine a flashlight and lower your cellphone camera and take a video until you’re satisfied the area is clear.
Or a blast of air will rustle up any debris enough (if any) in there to chase out any matter with cover off.
Usually there will be other evidence of rodent habitation (old or new) like acorns, shells, twigs, leaves, cotton fiber, etc on your engine tin.

The coming and going of a rodent would leave a messy trail so it becomes obvious they nested under the shroud. Operating the engine could have blown most of the old debris to the back and out of sight. Again if you’ve opened the engine compartment before any reason, it’s somewhat obvious but if you don’t think about it or ever thought a critter would take up residence there, likely it’s unnoticeable.
I live in mouse chipmunk retreat zone and make the inspections frequently and keep set traps year around.

There was a used 911 engine for sale on BaT auction site that had a perfect example of a rodent nest protruding from the fan, unfortunately I can’t find the old listing.

For what it’s worth, I have a 2.7L and No Aux Oil trombone or rad style cooler, and on the hottest, sunniest summer afternoon 85°-95°F , I’ve seen gauge at 220-240s° F maybe more but from idling too long at a freight train crossing (I pulled u-turn to go back) or heavy traffic or long lights.
Once moving along, the engine cooled back down to 190°-200° range for summer that’s expected, winter 20°-40° F I’ll see 180-190° range.
Just as important, Oil type and oil level along vehicle movement keeps temps down.