It is not possible to extract the seed phrase from a wallet.dat file created by Bitcoin core software.
This is because Bitcoin core does not use a seed phrase / recovery phrase to generate the numeric seed.
More generally, wallets that use seed phrases don’t store them on data files, certainly not in a way that anyone could extract them without knowing the wallet password.
The current version of Bitcoin core in early 2025 can still read wallets created by old versions including those in legacy format.
I have read of other tools that can read wallet.dat files, including one or more named PyWallet.
