I got a call from this number and it left an automated voicemail warning me of some sort of legality that is about to 'unfold' on me.

I attempted to call it back and it is no longer a working number. Scammy as hell

Some sort of legal thing was unfolding and I/my attorney had to call. Tried looking up number but got zero results. All left in a voicemail that must have started the second my greeting started b/c the recording was already half way through.

The numbers are spoofed or maybe to burner cell phones. The "track" people are reporting (...legal bs unfolding, you or your attorney must call....) is one of the more common scripts for a phony debt scammer or IRS scammer.  The idea is to scare you into paying a debt you do not and never did owe.
If you call back, the crooks think they are making progress; they see you as being gullible and they will call even more and become more threatening.  Ignore the calls, block the numbers.

Here is the message I received from this number.  It was an automated voice and the first part was cut off.  And then I had the same EXACT message from a different number a couple weeks later stating the same exact thing just a different phone number (the other number was 646-582-0688)

To tending your serious attention. Your case number is CF79621.  Ignoring this message will be an additional second attempt to avoid initial appearance before a magistrate, judge or the grand jury for a federal criminal offense. My number is (773) 536-1321. I repeat it (773) 536-1321. Do not disregard this message and do return the call. Now if you don’t return the call and I don’t hear from your attorney either the only thing I can do is wish you good luck as the situation unfolds on you. Goodbye.