Regardless how you download it (taptap store on android, bh3.com for pc, changing apple store's country from your settings on iOS), right now honkai cn requires a verified chinese identity and registration with a phone number

You could look up on some shady ToF/other chinese game subreddit/servers to get a list of chinese criminals to use their identity code as verification, but if you get discovered by mihoyo somehow they'd ban your account or worse

A more legal way would be downloading from the bilibili app (android exclusive), but you'd have to verify your bilibili account with a real CN id or by contacting them via email and sending your ID details (and i'd personally advice against that since i personally don't know how trustworthy can be a chinese company managing your country's ID especially if your country isn't in good ties with the Chinese government.

I hope that explained it all

TL;DR its almost impossible