Russia has large airpower equipped with heavy guided bombs (think JDAMs), which it only has started to use seriously due to the depletion of UA's long-range anti-air defenses (old Soviet S300 systems).
The problem is that Western long-range AA systems are exorbitantly expensive (~$1 bln for a Patriot system), take very long time to produce, and the West simply doesn't have it in quantities that could replace the rapidly depleting Soviet systems. Also, those expensive AA missiles get quickly attrited by cheap Iranian drones.
This is because the Western doctrine has always been about gaining air supremacy via airforce (fighter jets + AWACS + long-range air-to-air missiles complex), which UA doesn't have, and the US seems to be reluctant to supply Ukraine with all that — as they publicly say in the fear of escalation, but more likely due to the price tag.
So if that stance doesn't change, Russia would start bombing UA with heavy 1500kg+ munitions all over the place (inflicting very serious damage), and there is really not much UA could do with that, unfortunately.