Death of Stalin takes some fairly creative liberties at points, and compresses timelines, but the rough trajectory of Zhukov's portrayal is correct, and I'll go through a couple points.

First off, Zhukov has been censured and moved to a backwater posting after the war due to Stalin's paranoia - and also Beria, whom he largely blamed for stoking it - but by the time Stalin died, he was in the process of rehabilitation, but was not yet the Head of the Soviet Army as captioned in the film, nor even the representative of it as humorously implied (perhaps he was the representative at the buffet though). Rather, while he was included in the Guard of Honor, it was Marshal Vasilevsky who had the honor of giving a speech on behalf of the military. Both he and Zhukov had just been chosen as Deputy Defense Ministers to serve under Bulganin less than a month before Stalin's death, and wouldn't be confirmed in their positions until after.

It would then be several months before action was taken against Beria, and Zhukov's role there was basically as portrayed, if less exciting. Bulganin requested his presence at a meeting of the plotters where he was briefed on what was to happen, and given his appointed role of arresting office, intended in no small part to leverage his popularity as a war hero in the action. Just like the film, a buzzer was set up, and when pressed. Zhukov burst in with several other officers - armed with pistols though, not Kalashnikovs - and placed Beria under arrest.

From there Beria was dealt with swiftly, but not quite as quick as in the film, with several months between arrest and trial, although quickly executed after that, with Zhukov not involved in the trial or execution as shown in the film, although he took relish in his recollections of noting Beria soiled himself at his execution. Later in life he would call arresting Beria his proudest accomplishment, and his involvement helped finish his rehabilitation, setting him up to take over as Defense Minister in 1955, although he would find himself again kicked aside a few years after.

For further reading, Geoffrey Roberts' biography of Zhukov is the best English language one and covers the episode. Zhukov'a memoirs don't include it, but the most recent English language edition, published as Marshal of Victory includes several additional writings by Zhukov, including his reflections on the last days of Stalin, where this is covered.