My name is Lilith, I'm on the Social Care team at Shopify.
That's an interesting and great question! I'd be happy to help answer that for you here.
The short answer is that no, it won't reset annually.
At the moment and quite possibly for the foreseeable future, there aren't any limits to the size of the number.
We've seen stores with more than 300,000 orders and each with a sequential number since the beginning of the store opening.
If you do want to have that number change for different years you can change the prefix or suffix anytime. For example, you can change the suffix to
-2020 on the first of January in 2020 to start the year's orders with that suffix if you want to label them that way.
You can do this by going to Settings > General and scroll down to the standards and formats section. Check out my GIF below to see some examples of what you can do with the order number:
Ultimately, you don't need to change that since you can filter out orders based on many criteria in your order list, but if you prefer a visual you can definitely try that out.
Let me know how you do with the information above! I'm happy to answer any questions you think of as you work on your business.