There is no permanent peace achievable now. Russia invaded Ukraine in 2014 and there was 8 years of peace until they attacked again. They used the peace to re-arm.
The actual solution is escalating sanctions slowly, like a python, to demonstrate to the Russian people that Putin is not in control. A sustained quagmire and waning domestic support is a recipe for Russia pulling out of Ukraine on its own.
It’s been done many times: Korea, Vietnam, Afghanistan (twice!), Iraq. And those are just the ones that involved the US. Authoritarian regimes have to deal with domestic support too. They don’t just magically have unlimited resources to stay in power, especially when their army is outside the country.