Can I track my iPhone if is offline?

Hello ~ Take a look here for more info:

Use the Find My app to locate a missing device or item - Apple ...

If your iPhone, iPad, or iPod touch is lost or stolen - Apple ...

~Katana-San~

In specific and recent cases, potentially yes.

With iOS 15 and an iPhone with the Apple U1 ultra-wideband chip (list below), and in countries and regions where that U1 UWB chip can be enabled for this purpose, and where the user has not disabled this Find My tracking feature, and where there is sufficient remaining battery capacity to power the U1, yes, it is possible for other local Apple devices to detect a nearby and powered-off iPhone.

U1 is available in iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max, iPhone 12, iPhone 12 Pro, iPhone 12 Pro Max, iPhone 13, iPhone 13 Pro, and iPhone 13 Pro Max, and this Find My feature requires iOS 15, and requires another Apple device be nearby.

Think iPhone with an attached AirTag and you’ll be roughly correct about how this all works.

Otherwise, and as mentioned above, no.

No.