Bitcoin Core Walletdat Upd 2021

Yes. You don't need to update a lost file. Create a new Descriptor wallet and use the seed phrase from your hardware wallet or the original BIP39 recovery phrase. If you had an old legacy wallet (non-HD), the seed phrase didn't exist—you need the actual wallet.dat .

No. The file format does not auto-update just because you installed a new client. You must trigger upgradewallet RPC or use the command line. However, the blockchain data updates constantly. bitcoin core walletdat upd