Is it possible to extract the taproot internal key out of a P2TR address?
A P2TR address encodes a public key using Bech32m, which you can directly decode. This public key is often (as recommended by BIP341) the result of taking a different key (called "internal key") and tweaking it with the commitment to a taproot script tree. The internal key is not part of the address so it cannot be decoded from it and is only revealed when spending via the script path. Since protocols using taproot usually aim to use the key path whenever possible and some even make the script path unspendable (e.g. BIP86), you will not be able to determine the internal key for most taproot addresses (or even determine whether it exists at all).