All indications are that Russia and Putin simply can't allow Ukraine to win. Their attempt at (probably) Blitzkrieg and regime change failed, and of course they don't have the resources to occupy Ukraine.
So instead, unless Ukraine acceeds to their demands, they will get more and more bloody and bomb it to the ground. If that is the only course of action afforded to them, that is what they will do - as they have done in Afghanistan and Chechnya before.
This is monstrous and disturbing, but doing otherwise is seen as an existential threat to Russia. They have already shown they lack the power to pose any kind of threat to NATO (beyond nukes of course), so their only hope is to go all in on this.
There appear to be more nuanced balances than that. Putin avoided escalating the war via an explicit and public mobilization on May 9th, yet he certainly doesn't think he can easily win with the forces on hand.
Consequently, he must feel as though a public mobilization would have a higher risk (public opinion?) than reward (additional military manpower?).
In lieu of an influx of manpower, the existing Russian forces seem destined to grind down over time, both in terms of personnel and materiel.
IMO, he annexes Kherson-Crimea-Mariupol-Donbas, and calls it a victory.
Unfortunately, Kherson is still semi-resistant, Mariupol still (somehow!!) has active defenders, and ~1/3 of Donbas is still under Ukrainian control.
Donbas also has the misfortune of being an explicitly delineated area... so there's less wiggle room to redefine it as the portions already under Russian control.
And it's unclear that the Ukrainians would accept the above under any terms. Maybe "give us this and the rest of the country can join NATO"? But Kherson & Mariupol seem huge sticking points.
So the most likely outcome is that the war grinds on, with Russia attempting to achieve the above goals, Ukraine continuing to stubbornly resist (with NATO armaments and supply), and Russia continues to launch long-range strikes against western Ukrainian industry to increase pressure for peace. Which is to say, ugly.
So instead, unless Ukraine acceeds to their demands, they will get more and more bloody and bomb it to the ground. If that is the only course of action afforded to them, that is what they will do - as they have done in Afghanistan and Chechnya before.
This is monstrous and disturbing, but doing otherwise is seen as an existential threat to Russia. They have already shown they lack the power to pose any kind of threat to NATO (beyond nukes of course), so their only hope is to go all in on this.