It's kinda thinking about it backwards... Basically, there's the scriptPubKey and the witness... The scriptPubKey contains a SegWit v1 opcode for Taproot plus a 32 byte x-only public key. This is the address you send funds to. Then, to spend them, you have to sign a transaction, then include the 64 byte Schnorr signature in the witness to verify you own the private keys to that address. The efficiency gain here is that the 32 byte public key doesn't need to be included in the witness also (that would cost 8.25 bytes with the 4x witness discount-- 32 / 4 = 8, 1 byte for OP_PUSHBYTES32)