Did Russia left the war in 1918?

Yes, Russia left World War I in 1918 after signing the Treaty of Brest-Litovsk with the Central Powers on March 3, 1918. The treaty followed the Russian Revolution of 1917, which led to the Bolsheviks seizing power and seeking to end Russia's involvement in the war. The treaty resulted in significant territorial losses for Russia, as it ceded land to Germany and Austria-Hungary.