Can i see preview of both mobile and pc version at the same time?

im building a PC web.

i know i can see mobile version when i open the web.
but it’s very hard to design considering both device.
is there any better way to see both version or optimization of screens while building the web?

I’m not sure what you are asking. Can you try rephrasing your question?

This is how I am interpreting it. You are building a web app. But you want to be able to easily see what it looks like on mobile during preview?