Michael Kofman has a good roundup of the recent Vostok 2018 exercise, in which Russia claims that almost 300,000 soldiers took part. They tried out a new exercise concept with a greater focus on the free-play dimension than usually.
The recently held Vostok-2018 (September 11-17), which as the name suggests focused on the Russian Eastern Military District, offered an important deviation from the typically held command-staff strategic exercise which the Russian General Staff organises every September. In a standard exercise, an operational-strategic command (OSK) takes in forces from other districts and fields them in a particular strategic direction, organizing a hypothetical fight together with the General Staff in the theatre of military operations (TVD). But in 2018, Vostok was changed into strategic manoeuvers. Under this framework two military districts, Central and Eastern, divided into opposing forces to conduct manoeuvers in different strategic directions.
What really made headlines in the West was the scale of the exercise. 300,000 soldiers would make Vostok 2018 the largest military exercise in Russia since the legendary Zapad 1981, which was a demonstrative show of force to the Solidarity protest movement in Poland.
In reality, the exercise was rather smaller, probably not exceeding 50,000 participants (this is a guesstimate, use at your own risk) in the actual exercises, with most of the major events taking place at the Tsugol training range. The official numbers given likely represent the total forces on paper from the Central and Eastern Military Districts: often the Russian General Staff will count an entire brigade or division as having participated even when their contribution is only one unit.
50,000 soldiers is still an impressive exercise, but it is not historical. As Kofman pointed out in a different post, Russia usually inflates the numbers for their Vostok exercises and underreport for the Zapad exercises. This way they can pretend to adhere to arms control agreements like the Vienna Document because exercises in Europe look tiny, but they also get to report sensational numbers for exercises East of the Ural Mountains.