This is a draft answer (incomplete).
To get set up on Signet ie sync the Signet chain and claim some Signet Bitcoin, follow these instructions. (You can run a Signet node in parallel with your mainnet node, ie same hardware)
You now have funds at a non-P2TR (i.e. SegWit v0, bech32) Signet address. Now you need to generate a P2TR address to send funds to so you have funds at a P2TR address (so you can spend from it).
You can't generate a P2TR (bech32m) address in the wallet using getnewaddress:
./bitcoin-cli -signet -rpcwallet=insert_wallet_name getnewaddress "" "bech32m"
returns
error code: -8 error message: Legacy wallets cannot provide bech32m addresses
So you need to construct a Taproot descriptor manually and then import it into your descriptor wallet.
TBC