The seed phrase cannot be extracted from the Wallet.dat file generated in the Bitcoin Core Software.
This is because Bitcoin Core does not use seed phrases / recovery phrases to create numeric seeds.
More generally, wallets using seed phrases are not stored in the data file, and others are not able to extract without knowing the wallet password.
In early 2025, the current version of Bitcoin Core can still read a wallet made of existing versions in the form of legacy.
I read another tool to read the Wallet.dat file, including one or more pywallet.