So how will the carrier strike groups be used? Sink Chinese navy ships? That's one step up the escalation ladder.
China will reciprocate with sinking some escort ships of the carrier groups, just to make a point and demonstrate their hypersonics. Another step up the escalation ladder.
At which point, the carrier groups either back off to de-escalate and avoid losing a capital ship. Or stay there and continue the escalation. As mentioned in another comment, this is projected to stop the Chinese invasion at the cost of losing two carriers. That is, if WW3 doesn't start first.
The underlying assumption is that the US intends to escalate to a full-scale war if China does not back off. If China does not believe in that, the US Navy is just a bunch of expensive but inconsequential toys that can be safely ignored.
If the deterrent works and China does not invade due to the risk of a major war, it's the best-case outcome. If it fails and a war breaks out, massive casualties are likely. Wars are usually not as one-sided as the ones the US has fought in the past decades. But it would not be WW3, as most countries have no reasons to get involved.
China will reciprocate with sinking some escort ships of the carrier groups, just to make a point and demonstrate their hypersonics. Another step up the escalation ladder.
At which point, the carrier groups either back off to de-escalate and avoid losing a capital ship. Or stay there and continue the escalation. As mentioned in another comment, this is projected to stop the Chinese invasion at the cost of losing two carriers. That is, if WW3 doesn't start first.