Whales trade outside the market, or what is known as Over-the-Counter (OTC) market[1], which starts from 50k per day and reaches millions, but the problem is that these markets are highly organized and it is impossible to do them without identity verification procedures, and trading such amounts daily means that they are subject to taxes and therefore you may be accused of money laundering and tax evasion.
OTC is option but must KYC and does not match with OP.
There are centralized exchanges OP can use to trade if he already has Ethereum. Deposit and sell Ethereum and use USDT or USDC to buy Bitcoin. Withdraw it gradually to not exceed maximum withdrawal of daily limit for non KYC account. Because using centralized exchanges are always risky, OP must deposit, trade, buy Bitcoin, withdraw it each day. I don't advice OP to send all Ethereum in $M equivalent in one deposit and leave it on exchanges, and wait for daily withdrawal. They can scam OP by freeze account and reject withdrawal.