I'm sorry about your stolen Surface. Here's what you need to do right away: Use Find My Device to lock it—this will require your Microsoft account password to unlock (not just a PIN or fingerprint). Then immediately change your Microsoft password to something strong and enable two-factor authentication. This protects both your stolen device and your new laptop. The lock won't help you get the device back, but it will keep your data secure.
Go to: https://account.microsoft.com/devices
Select the stolen Surface Laptop 5
Click Find my device → Lock