You can check out the below list to see Dex exchanges, some exchange in the list are centralized but KYC is optional it’s better to avoid them though.
Where can it be done? You can use any Dex that allows you to decide which coin you want to sell and which one you want to hold, create, and order, and you can place to sell BTC in place for menero (XMR). The next person doesn't know who you are, and you also don't know who the next person is.