This is working fine
window.open(yoururl, "Popup", "location,status,scrollbars,resizable,width=800, height=800");
For all parameters see window.open
Edited Date:- 12th Aug, 2021
If you does not want to use JavaScript Function, then You can write Inline Script for Open Page in New Windows, & it is support all the modern browsers
<a href="https://stackoverflow.com/" onclick="window.open('https://stackoverflow.com/', 'newwindow', 'width=400, height=250'); return false;">with href</a>
<a href="#" onclick="window.open('https://stackoverflow.com/', 'newwindow', 'width=400, height=250'); return false;">without href</a>
You can see Live Working example on this jsfiddle.net link