Most modern GPS trackers for cars come with SIM cards that can be used internationally. Depending on the make and model, it may be limited to North America- but others are supported further afield. It is worth checking out the SIM details on the trackers you are interested in to see if they are suitable for use in the countries in which you plan on using them.
If you are ordering a device from outside the US, you can get SIM cards set up for your location. International plans may vary depending on the country you are based in and the provider you choose.