There's no need to consolidate them into a single UTXO before using a mixer. For future privacy, opting for three or more mixes is recommended. Afterward, designate these UTXOs as "mixed" and label upcoming ones as "kyc" or "non-kyc" for straightforward privacy management in any transaction.
However, it's essential to note that regulators frown upon mixers. In the US, certain centralized exchanges flag UTXOs from mixers, and Chainanalysis scrutinizes your last three hops for this. This can be circumvented by conducting three transactions before sending to such exchanges. In the EU, a new law by the end of the year may label self-custody and mixers as "risky," requiring proof of fund origin. Regularly exporting your buy history from an exchange is crucial.
Nevertheless, these considerations become irrelevant if your intention is not to sell on a centralized exchange. Peer-to-peer selling remains a viable option.
But why would you sell hardest asset known to mankind for toilet paper anyway? 😊