If my Canadian iPhone 14 needs to be fixed or replaced in the US, does it still come with a SIM tray?

If it needs to be replaced in the US, it will NOT come with a Sim tray. And Apple won't replace a phone purchased in a country with different regional differences with a different model. So, if your phone is being used in the US and it breaks to the point it needs to be replaced, you will need to take it to Canada.