I have not gone back to rewatch all the games the US played so this is strictly from memory. I think we used some 4-3-3, 4-5-1, did we use 4-4-2? I thought the 5-4-1 we used at times to keep England and France from scoring was pretty good. What's your thought.
We also used a 4-1-4-1 during the Netherlands match. I thought it was very smart and effective way to defend once we had the lead and with our talented midfield, we were able to pass out of traffic to counter quickly and break down the defense.
They started every game of the WC in a 4-3-3. In fact, they've started their last 45 games in a 4-3-3. The last game the USWNT didn't start in a 4-3-3 was against Australia in the 2017 Cup of Nations, which they lost 1-0. They were in that 4-4-2 for 5 straight games and the 7 games prior to that they played a variation of the 3-back. In the 2019 WC... After going up 3-0 against Thailand, they switched to a 3-3-4. Against the 5 European teams, they switched to a 4-5-1, 5-4-1 or 4-1-4-1 to close out the games.
Formations are mostly meaningless. It is about instructions. I have seen a 3-4-3 that was really a very defensive formation. It was effectively a bunker. I have also see a 6-3-1 that was VERY aggressive producing a varied and potent attack by sending different sets of defender forward at different times. Some formations morph more easily. The 4-4-2 and the 3-4-3 are the two generally most commonly discussed and used with the 4-3-3 following closely. The reasons for those are that those formations are some of the easiest to change in nature by simply changing instructions to one or two or, sometimes, three players. The importance of a formation is not what it can do but rather how it can answer what is happening on the field.