Sure they can, and did at the beginning of the war. A lot of good that did. Protests don't always work.

Do you really think civilians can overthrow the government in Russia? If there is one thing modern Russia is good at, it’s stomping out civilian protests. Can you really blame the people there for not wanting to risk a 15-year prison sentence or death just to express their disapproval of a war that’s going to continue regardless? I highly doubt that you or anyone else here would do anything different in the same situation.

I don’t support Russia’s war in Ukraine, and I don’t understand why so much aggression is being directed at Russian civilians.