So long as you lead with confidence and do not show them any anxiety, while presenting it as a family adventure, then you'll be absolutely 100% fine.
We have moved many times, including for 3rd grade, from the West coast to the East. There is always a settling in period, but if you're active about getting your kids involved in after school activities and having play dates, it works quite quickly for them. And you kind of have to resign yourself to it taking a bit longer for you.