How to change Google Chrome User-Agent string on iPadOS
TL;DR: No, you can't. Unless there're any other browsers that support switching User Agent natively.
It's sad news, since all browsers on iOS/iPadOS share the same technology (WebKit) under the hood as Safari, per requirement by Apple. You can't install existing Chrome extensions to switch UA string either (also not doable on Chrome for Android).
WebKit surely provided abilities to change UA string, but Chrome on iOS sadly didn't expose this feature.