Knight Hider is correct. A single seed phrase of any length can be used to (almost certainly) generate every possible bitcoin address. This is thanks to derivation paths.

When you use a seed phrase to generate an address, then most wallets will start to do so at a derivation path such as m/84'/0'/0'/0/0. Each address you generate will have a unique derivation path. So, just how many different derivation paths can you have.

Well, as per BIP32, extended keys have 1 byte for the level they are at. 0x00 for the master key, 0x01 for the first level, 0x02 for the second level, and so on, up to 0xFF. This means you can have a total of 255 levels after the m. It also allows 4 bytes for the index. This means a total of 2³² possible indices for each of those 255 levels. So a single seed phrase can generate (2³²)²⁵⁵ private keys. This number works out at 2.5*10²⁴⁵⁶, which is many orders of magnitude higher than the set of all possible private keys (a little less than 2²⁵⁶). This means that not only can any seed phrase (almost certainly) generate any private key at the right derivation path, but any seed phrase can generate any private key billions and billions of times and many different derivation paths.