My iPhone 13 Pro Max was stolen yesterday, can I still track it with the IMEI?

No iPhone can be tracked by IMEI except maybe by court order. Even then, they will not allow you to track it yourself.

Find My iPhone is for finding lost iPhones. Stolen devices are another matter, best handled by law enforcement. And as you have learned, they rarely act on such small priced items. Yes, even top model IPhones are usually considered too small and too easily stolen to act on.

Your next step is to use AppleCare+ with Theft and Loss protection if you purchased it, or your own insurance. If you purchased it with a credit card, your card issuer may provide some form of insurance.

If you had Find My iPhone enabled, the thief will never be able to use your stolen device. But that will not stop them from trying to quickly sell it to someone who does not know about Activation Lock.

Beware of a common phishing scam: You may get a text or email from “Apple” or “Apple Security” (or sometimes “Police”) saying your phone has been found and to click on a link to see its location. This is NEVER from Apple or from law enforcement; it is from the thief or fence to steal your Apple ID and identity. Delete any such message without responding to it. Apple never gets involved in lost or stolen devices→Avoid phishing emails, fake ‘virus‘ alerts, phony support calls, and other scams

your options is

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

apple can't legally act as a private investergater finding your lost property

your local law enforcements can if given the IMEI get a warrant and force your countries carriers to triangular track the phone, its mostly used in missing persons cases, and it's cost would likely be that of 10 iphones though