Can I track my iPhone if it’s offline

No. See this Apple support link—>If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

Lawrence Finch wrote:

You are correct, I was wrong. While it doesn’t say so, however, Bluetooth must be on for offline Find to work.

That’s not going to happen very often. 😎 It would be nice if Apple made it clear that Bluetooth must be turned on in order for it to work.

You can locate it if offline finding is enabled.

Locate a lost or stolen device - Apple Support

You are correct, I was wrong. While it doesn’t say so, however, Bluetooth must be on for offline Find to work.