I know everyone's having fun mocking Putin and the Russian performance in this war, but let me play Devil's Advocate for a moment (I went to a Jesuit school, it's what we do).
Russia has a real chance of victory in this second phase. They've paused major operations for several weeks, rested and repositioned forces from northern Ukraine and are preparing the ground for a major wide-front invasion with multiple prongs. The stage is set for them and they have the initiative.
Russia has lots of things going for it. They've got air supremacy (although not full dominance), artillery supremacy and significant advantages over the Ukrainians in terms of heavy ground forces - both in terms of numbers, quality and overall mobility. Russia can bring substantially more firepower to any one point at any one time than their opponents can, and in war that matters
They've also got advantages in terms of strategic mobility. Russia basically has control of when and where it attacks. If the Russian Army does encounter strong opposition, it can re-position/reset its axes of advance, or concentrate forces on completely a different axis.
Most of Ukraine's manpower is relatively static/foot mobile and comprised of lightly armed reservists. These troops work well when defending fixed positions against other light forces and 'Thunder Run' style rapid attacks. I question their ability to survive and contribute meaningfully on a battlefield being prepared by artillery and against an opponent using proper combined arms tactics with heavy forces.
Russia and it's leaders - both political and military - aren't dumb (no matter how we might like to deride them). It's armed forces got a rude shock in the initial phase, because their perception of reality and the actual situation on the ground were very different.
I suspect though that they have now had time to adjust and figure some things out. Like logistics. And communications. And SEAD.
Worst case for me is the Russia's second phase operation fixes some of Ukraine's heavy regular army units in place the East of the country, and then manages to destroy them with overwhelming firepower. Then they use these openings in the front to break into open territory where they're opposed by light/reserve/less mobile forces. There's little to stop them completing a major encirclement, with forces linking up from the north and south.
Surviving Ukrainian troops are forced to withdraw westward or are trapped in a pocket. Either way, very heavy losses ensue - including most of Ukraine's heavy equipment and regular army troops. Ukrainian general staff is forced to give up on a wide front in eastern Ukraine, pulling back to the northwest to defend a shorter line (maybe Dnipro-Kharkiv, or Kremenchuk-Poltava-Kharkiv if things really go bad).
Russia ends up controlling everything on the eastern bank of the Dnipro River up to Dnipro City itself and then a large chunk of the country immediately north of that all the way up to the Russian border. It then halts its advance at whatever new defensive line the Ukrainians manage to establish, settles into a defensive posture, declares a 'mission accomplished' with a parade through Red Square and calls for a general cease fire.
Ukrainians become disenchanted with their government after losing the war, blame Zelensky for getting them into something they could never win and vote him out a few years later. In his place is a Russian-friendly candidate who promises to restore good relations with Russia in exchange for some territorial adjustments. He signs a peace treaty, ceding control of certain territories to Russia on the promise of 'free and fair' referendums on whether they want to be part of Russia or not.
End result, Russia acquires ~20-25% of Ukranian territory, controls 80% of its access to the Black Sea and ends up with four or five cities with populations of more than 250,000.
Here endeth the fantasy. Which - in my own not so modest opinion - is not actually that fantastical.
(Of course, I'm ignoring the wider economic and geostrategic issues here. Just assume that Russia's economy is f*cked but it can still win the war using available reserves)