All i know if you don't want to someone track your transaction you should use any well known coinmixer. You can find here some.
Well that's a common trick but i guess it's not good enough. Cause it's depend on how much coin you want to withdraw. Because many of those exchanges will be want KYC if btc withdraw amount is high (more than 2 btc or depends on separate exchanges).
That was good anyway.
2) send your BTC to an exchange like bitbox, kucoin, huobi ... then buy monero, send them to another exchange like bitbox, kucoin, huobi ... and buy back BTC
But what if those exchange are linked together so that monero transaction between two of them will be identified.
But what if those exchange are linked together so that monero transaction between two of them will be identified.
Well that's a common trick but i guess it's not good enough. Cause it's depend on how much coin you want to withdraw. Because many of those exchanges will be want KYC if btc withdraw amount is high (more than 2 btc or depends on separate exchanges).
The most secure way: Buy a mining farm and mine the virgin coins 
That was good anyway.