Does Watch Series 5 work with iPhone SE? On Apple's fine print it says:


  Apple Watch Series 5 requires an iPhone 6s or later with iOS 13 or later. 


So I'm not sure whether this implies iPhone SE as well.
Yes, the iPhone SE is supported by Apple Watch Series 5 as it was released after the iPhone 6s in March 2016, as long as the device is running iOS 13 or later. 

I can confirm the device functions perfectly.