Could bitcoind support SPV mode by setting different args
No. bitcoind does not have a SPV mode at all.

Pruning is not the same thing as SPV because a pruned node still downloads and verifies the blockchain. Just instead of storing all of the blocks in the blockchain, it discards  blocks when they become deep enough in the blockchain. This reduces disk usage but does not effect security, bandwidth usage, or initial sync time. Pruned still receive all blocks and transactions, validate them, and relay them.

Conversely, SPV wallets do not even download or verify the blockchain at all. They only do simple verification, not full verification. SPV wallets only download block headers and check the proof of work. They do not and cannot check entire block validity like full nodes can. This allows SPV wallets to have a much much faster initial sync time at the cost of security. SPV wallets do not receive all blocks and transactions and thus cannot validate or relay them.