How do I get TikTok on my iPhone?

You cannot as its currently not available in the App Store.

Click here ➡️ About availability of TikTok and ByteDance Ltd. apps in the United States - Apple Support

Run for Congress.

Get elected and form a coalition.

Gather enough support to repeal the law or scrape together around a billion dollars and buy Tik Tok so it has a US owner.

Jimpsl wrote:

Just download from App Store.

This is NOT good advice. TikTok is not available in the App Store. It is banned by law in the US.

Just download from App Store.