I do not advise you to extract the private key, a.k.a master private key, as wallet.dat allows you to encrypt your private key with a password, and the stronger and unique it is, the more difficult to hack your wallet.

bitcoincore wallet is not a good option for beginners so why not use any SPV wallet like https://electrum.org or https://sparrowwallet.com where you get your 12 words wallet seed which can be easily stored offline.