If Russia could bomb, they would. They have no problem flatting towns with artillery. In fact, that was their MO in Chechnya and Syria as well as Ukraine. But strategic bombing requires air superiority, which Russia has yet to achieve and that’s not even taking into account surface-to-air defenses.
That said, I believe Ukraine can and will defeat Russia militarily. By that, I mean eject Russia to the 2014 borders. Russia’s sole advantage is the enormous amount of soldiers and equipment, especially artillery which at one point was something like 10:1 over Ukraine. But by all accounts Russian soldiers and equipment have been performing poorly on the battlefield.
Similarly, Ukraine’s military hasn’t been great, but by all accounts has been getting better and their equipment is getting a lot better. Their training has been getting better too. It is happening slowly, but it is happening. To that end, Russia has not had a significant military victory since July and has been forced into two major retreats.
I don’t know how this plays out over the next few months (Russia is reportedly preparing for another mobilization early next year) but it seems that Ukraine will increasingly be able to gain localized military advantages and use that to exploit breakthroughs. At some point, Russia won’t be able to stop it.