No. An attacker trying to brute force a single private key is just going to attempt to brute force the private key rather than the seed phrase it was derived from.

If I generate a private key, to check for an address collision all I have to do is use elliptic curve multiplication to turn it to a public key, and then hash it a few times and convert to Base58.

If I generate a seed phrase, to check for an address collision I first have to go through 2048 rounds of HMAC-SHA512, and then multiple further rounds of HMAC-SHA512 to work down the derivation path to the relevant account and address index, and then elliptic curve multiplication and hash as above. It is a far more time consuming process. It makes much more sense for an attacker to try to brute force the individual key, which has the exact same security if you use 12 words or 600 words.

And to brute force a 24 word seed phrase, an attacker needs to generate all possible 24 word seed phrases. There are 2²⁵⁶ valid 24 word seed phrases, which is actually more than the number of valid private keys, which is slightly less than 2²⁵⁶.