I already told you how: https://groups.google.com/g/bitcoindev/c/FpSWUxItXQs

Nothing is enforced. That kind of things will be optional. As long as you want to have a full archival node, and store everything, including a lot of spam, then you will just run the official version, with the default settings.

And if you will need to have some spam-resistant node, then you will use a different version, which will be compatible, while also rejecting spam, or at least not storing it permanently (or even not downloading the spam at all, and processing some proofs instead). Your node, your choice.

So, do you have a full node? Do you have a problem, to sync it here and now? Because guess what: people are lazy. As long as nodes are not crashing, as long as disks are big enough, and as long as node operators are not sued, because of broadcasting copyrighted material, and as long as nodes can verify the chain faster, than it is made, then nobody cares. People will start to care about spam, and fix things, when they will be directly affected (and many users from forums or exchanges won't be affected at all, because they already use SPV wallets, or they have many altcoins, and they don't care about Bitcoin as a payment system, but care more about blockchain as a solution for all problems in the world).

So, are you affected here and now, to introduce some solutions? If you are, then you can help to discuss or build some of them. But they won't be globally enforced, because the majority wants to have a spamchain, so the spam-resistant version won't be enforced on everyone, as long as spammers have enough resources to keep spamming, and cooperate with spamming mining pools.