web3.eth.accounts.create()

address: '0xB9b1415Dbd1B3C9a5890433DF8B2b389445CC6Fa',
  privateKey: '0x498262a4afde2bdd9e1bef3aafc6442ec36ccf167e527457a211118de93346ba',
  signTransaction: [Function: signTransaction],
  sign: [Function: sign],
  encrypt: [Function: encrypt]
  
  
  
  

the private key is here '0x498262a4afde2bdd9e1bef3aafc6442ec36ccf167e527457a211118de93346ba' this is of a 64 hex format.

so the 32 bytes length private key is 498262a4afde2bdd9e1bef3aafc6442ec36ccf167e527457a211118de93346ba

(remove the 0x)

Ethereum uses 32 bytes (which is 64 hex characters) long private keys.

You can access the private key generated using the accounts.create() method (docs) in the privateKey property.

const account = web3.eth.accounts.create();
console.log(account.privateKey);