The idea that Russia is looking to conquer all of Ukraine and more is simply war propaganda.They probably never wanted to permanently hold all of the territory (especially not predominantly Ukrainian-speaking regions in the west).
But it definitely was their stated objective from the very beginning to decapitate the country's current leadership, and install a permanently "friendly" (to Russia) government in its place. Not to simply grab the 4 regions in the east -- which they've still not been able to fully take a hold of, despite explicitly claiming to "annex" them.
The idea that the disastrous initial attempt to encircle Kyiv (and the failed attempt to take Odesa) was some kind of brilliantly executed feint to obscure their "true" current (and ever-shrinking) objectives - that, I'm afraid, it simply "war propaganda".
It makes no geopolitical sense for them to really conquer much more than they already have.
Nothing about what the Russian Federation has done makes any kind of geopolitical sense. It's all just a giant (and incredibly murderous and destructive) fantasy.