Yes, Russia could always do something dumb. So could India/Pakistan along their contentious border. Or North Korea getting spicy again at South Korea. Or China firing nukes across the Taiwan Strait. Or an infinite number of scenarios in the Middle East involving Israel.
The mere existence of nuclear weapons in the hands of any country is a nightmare that it hurts to think about.
That said: the USSR/Russia, the U.S., and every other nuclear-armed power have fought multiple if not dozens of wars since acquiring nuclear weapons, without ever actually resorting to using their nukes, with the sole exception of the U.S. over Japan in 1945 (which can be considered a special case, an exception that proves the rule, as this was during a brief window when the U.S. was the world’s only nuclear power and didn’t have to fear mutually-assured destruction).
All of which is to say, a nuclear taboo has held since 1945, and there’s little reason to think the latest conflict that happens to involve Russia is going to change that.
It’s fair to say that having nuclear weapons grants Russia effective immunity from being invaded on its own soil and a significant degree of diplomatic deference (hence why it’s taken so long for the U.S. and Germany to send over their best tanks to Ukraine), but nuclear privileges are not unlimited. If we allowed nuclear blackmail to become normalized, there’s no telling where it might lead. But for starters, nuclear proliferation would increase exponentially, multiplying doomsday scenarios ad infinitum.
Taking the long view, it actually reduces worldwide nuclear risk to show other countries thinking about acquiring nukes that Russia can’t bluff its way to victory with nuclear threats despite losing or at best being stalemated on the ground.
For now, the fight over Ukraine proceeds in ghastly, though strictly conventional terms.