How to validate page layout structure as part of regression testing

Hello!
That is a great question - I havent tried nativaly with UiPath.
I am guessing you are looking for Visual Testing - there are a few platforms specialized in that, like Percy ( Visual testing and review platform | Percy by BrowserStack)

You might be able to do something a little more simplistic by comparing 2 screenshots - one used as a “golden image” on how the website should look, and another one took at runtime to validate if the website layout has changed. The forum seems to have several different approaches - maybe try this one? Comparing Images - Help / Studio - UiPath Community Forum

Good luck!