Only way to know for certain is someone pulling out a '17+ thermostat and looking at it, but then again my stock '14 didn't have any marks on it to indicate what temp it was. All references I could find don't indicate a change in thermostat for '17+ model years, but I'm not certain without more concrete evidence.
Here's my temps lifted from a post in my build thread.
https://www.fiestastforum.com/forum/threads/3074-koozy-s-ST?p=181754&viewfull=1#post181754
Stock
Temps during a spirited canyon run with the OE Radiator and Mishimoto Oil Cooler. DHM turbo on E30 tune.
Temps during a spirited canyon run on same road with the Mishimoto Radiator and factory OE oil cooler. Stock turbo self tune Stage 3 91oct.