Yes, but isn't that just holding crypto? Once you have it the trades are anonymous in decentralised systems and no one can see what you're using it for. I understand that where resources are available, investigations can be done, but it's not like Visa/Mastercard where all transactions are recorded to the minute detail.
While not like visa/mastercard, the transactions stopped being anonymous the moment you had to register to acquire crypto. Its part of AML/CTF regulations the world over. The transaction from one wallet to another like me paying you for drugs or a hitman is as easily tracible as seeing a transaction on a visa or bank statement. Exchanges keep records as does the block chain. So for most people, anonymity is no longer possible.
Where investigations are required is when one needs to marry up multiple sources that make up a block coming into a wallet. But the incoming wallet is known. as are the outbound wallets, there could just be many of them.
There are a few anononymising methods used by criminal enterprise. One involves a handful of small exchanges hat let you transact up to 1.5k without ID. one such exchange is Paxful. Paxful lets you buy crypto peer to peer using gift cards like amazon or itunes etc - they accept i think like a 120 different cards. Ever wonder why scammers are always getting their victims to pay for their ATO bill with gift cards? Now you know.
An expensive Bot exists that allows you to automate the creation of these accounts and trade amongst your own accounts up to the limit to obfuscate the transactions several times and then send the crypto where ever you want. That's when it becomes difficult to identify. Especially if the trading is conducted through SOCKS and via botnets to further obfuscate. its too high effort for the everyday person. But for the most part anonymity is no longer a thing, regulation is in and surveilance is excellent.
Crypto exchanges are required to surveil just like share market exchanges are - Nasdaq have a platform called SMARTS that is industry standard in share market exchanges. They also have a crypto surveillance platform built on the same tech.
https://www.nasdaq.com/solutions/nasdaq-trade-surveillance