(adsbygoogle = window.adsbygoogle || []).push({}); is it possible to get xp in a private match?

No it isn't. The Global XP offsets can only be changed in public matches. And are limited to a maximum increase of 65594 XP per game. You can spoof people's ranks in private match but it won't stick. I have a GSC Script which you can use to rank people up in public matches if you would like it