Designing and Testing for Reflow

Hi W3 Community,

Inquiring how others test their web pages to meet Success Criterion 1.4.10
Reflow (Level AA). I tried zooming in a Chrome window on my large-screen
monitor to 400%, a Chrome window on my laptop monitor to 400%, and used
inspect to resize the window size to 320px wide. Unfortunately, all have
produced different results.

Looking to see if anyone can provide the most correct/proper way to test
out a website in Chrome.

Thanks for your help!

Sabrina