Exchanges do not replace a mixer or a proper coinjoining service. You can sue it it you're trying to blur the transaction trail at a basic from family and friends but your transactions are logged by the exchange and they are liable to share that information and can lose it through a breach.
exch.cx is a
no-kyc instant swap exchange, there is no registration or logs and they don't have any private information about their customers to share, only their addresses. exch may not be a mixer in itself, but it is a swap exchange that is privacy focused and they also do not aggregate utxo's on one address, so it becomes very difficult for blockchain surveillance companies to trace or track where the coins came from.
Meaning if i do multiple transactions using that Instant Exchange and convert Bitcoin to Litecoin. (The destination address of LTC remains the same in all the transactions )
It is a good option for privacy, but you have to do your own part and use a different address in receiving your LTC. Exch.cx will provide you with a different address to deposit your BTC and since they don't aggregate utxo's your LTC will come from a different address, so when swapping multiple times, it is great for your own privay to not reuse receiving addresses.