Is this approach of returning different content depending on IP beneficial for international SEO?

[Mickooo]

I've decided to use sub folders for my site, and from everything I've read online it seems I shouldn't change the page content depending on IP, yet I know of a successful well funded site that hires full time SEO staff that does just that, and I'm wondering whether they know something I don’t which is helping their SEO.

From everything I've read online this is the format I think I should use:

mysite.com/us/red-wigs

mysite.com/gb/red-wigs

mysite.com/red-wigs does not exist

This is the format the other site is using:

othersite.com/red-wigs (from US IP address)

othersite.com/red-wigs (from UK IP address)

othersite.com/gb/red-wigs

The content on othersite.com/red-wigs is identical to othersite.com/gb/red-wigs when loading from a UK IP address, and a lot of URLs without /gb/ are being returned when searching google.

The benefit I can think of that they are gaining is US pages which are being returned for UK based searches will return the correct content. Are their any other gains to this approach? I'm concerned that if I use this approach for different languages then the radically differing content of othersite.com/red-wigs depending on the location of the crawler might confuse google - also generally changing content depending on IP seems to be recommended against.

Thanks

[Mobilio]

Canonical and hreflangs are always full url and you can't use relative addresses:
https://developers.google.com/search/docs/advanced/crawling/localized-versions?hl=en
"Alternate URLs must be fully-qualified, including the transport method (http/https), so: https://example.com/foo, not //example.com/foo or /foo"
https://developers.google.com/search/docs/advanced/crawling/consolidate-duplicate-urls

So you need to remake your example with full URLs like:
protocol://domain (with or withour WWW.)/path/to/some/folder/

Also avoid geotargeting for IP.  This can went you on deep issues since Googlebot is crawling mostly from US IP. Therefore Google NEVER can see your UK links. Source:
https://developers.google.com/search/docs/advanced/crawling/locale-adaptive-pages?hl=en
"If your site has locale-adaptive pages (that is, your site returns different content based on the perceived country or preferred language of the visitor), Google might not crawl, index, or rank all your content for different locales. This is because the default IP addresses of the Googlebot crawler appear to be based in the USA. In addition, the crawler sends HTTP requests without setting Accept-Language in the request header."

Regards,

Peter