Two contrasting posts.
I'd still wait for an official announcement by the SDF themselves.

MT @[email protected] [White House reporter for WSJ, 15 minutes ago]:
White House Press Secretary tells reporters that the territorial ISIS caliphate has been 100 percent eliminated in Syria. She directed reporters to DOD for additional information. She showed reporters a map of Syria. - via travel pool

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RT @[email protected] [CNN reporter, 11 minutes later]:
Planes still flying over Baghouz. Airstrikes within the last hour. Machine gun fire in the distance. Is #ISIS totally defeated? Essentially yes, but there are still โ€œhundredsโ€ of holdouts per SDF. Thatโ€™s what were seeing here in eastern #Syria.

Update, just now...

RT @[email protected] [CNN reporter]:
Another airstrikes now, tracers, heavy machine gun fire on eastern end of Baghouz. I guess not everyone heard the White House statement re 100 percent elimination of #ISIS territory.

RT @[email protected] [head of SDF Press Office in northern Syria]:
Heavy fighting continues around mount #Baghouz right now to finish off whatever remains of ISIS.