Provided the US took Canada, whether that is during the Revolutionary War or the War of 1812, would the US look for more or less of Mexico?
The US would already have a large and relatively secured access to the Pacific here. It would also have more free states, which would change US politics on slavery quite a bit over 30+ years.
Then, the US has a potentially troublesome French Catholic Quebec, along with a larger white and Anglo population.
Huge variables here.
What do you believe America’s policy towards the South West would likely be?