In order to do that Russia would have to take Kiev, which is the seat of Ukrainian government, and topple the Zelensky administration.
We now know that a deal was being made between the Zelensky regime and Russia to negotiate a peace that would result in exactly those terms, and that the US and its NATO allies in the EU managed to put the kibosh on it. Whatever else you can say about Zelensky, he knows how to broker a deal. There is absolutely no need for the Russians to reduce Kiev to a smoking ruin to acheive their objective. Though no doubt Putin is willing to do that if he thinks it's necessary to achieve his goals. But that's not what the Russians have said. It's worth watching actions and words. The Russians are dead serious about not having a NATO aligned Ukraine on their border, and incorporating the Russian speaking provinces into Mother Russia.
We don't have to like it, but unless we want to follow our feckless leaders as they blunder us into WWIII, we might want to examine the actual record before blithly making assumptions that are not supported by the facts.
“We now know that a deal was being made between the Zelensky regime and Russia to negotiate a peace that would result in exactly those terms...”
No, we don’t. And you sure as hell don’t. Even Naftali Bennett — who was involved in the negotiations — did not say that.
“...and that the US and its NATO allies in the EU managed to put the kibosh on it.”
Again, that was recently refuted by Naftali Bennett and his security advisor Eyal Hulata.
They said negotiations ended when the atrocities at Bucha were discovered. Thay also said that both Ukraine and Russia are too entrenched and that neither side is in any mood to make any concessions to the other.
https://www.axios.com/2023/02/22/israel-russia-invasion-ukraine-bennett-mediation-failure
Also, Bennett said that during his mediation, Putin dropped his vow to seek Ukraine’s disarmament and Zelenskyy promised not to join NATO, the latter of which should silence — but won’t — all those kremlin sympathizers here on FR who wax indignant about NATO.