MrBadger
Badger out
No, the system will tell you if a tyre drops below 20% of the cold set threshold, or 20% below the maximum temperature that has been achieved during a trip.
I don't know about the 20% maximum temperature, but on the non bluetooth Model 3's when the TPMS was default at 42psi cold the TPMS warning would be triggered at a 10% drop, ie 4.2psi, or fractionally under 38psi - and confirmed with experience. Don't know if things have changed since.