Hi Brooke,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
The Surface Laptop 7th Edition has been designed with a 13.8-inch or 15-inch HDR touchscreen and an ultra-thin chassis. Given these specific dimensions, it's important to get a case that is made to fit this model to ensure proper protection and functionality of the ports and hinges.
Here are the dimensions and weight of the Surface Laptop 7th Edition. Surface Laptop Essentials Bundle, 7th Edition Copilot+ PC - Microsoft Store

While I couldn't find information on the exact compatibility of cases from previous models with the new Surface Laptop 7, it's generally recommended to use a case designed for the specific model to avoid any issues. Cases for previous models may not fit perfectly due to changes in design, dimensions, or port placement.
/**Update**/
This page provides cases for Surface Laptop 7th Edition, and it can also help you find accessories designed specifically for your Surface device. Accessories Designed for Surface (microsoft.com) ****
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist