Michael the younger brother of Czar Nicholas II, does accept that his brother nominated him as his successor. He proclaims himself Czar. He knows the mood of the people and promises to end the war. He instructs his envoys in Sweden to speak with their German counterparts to obtain an armistace. Surprisingly the Germans agree. The Western Allies are furious. Michael agrees to surrender The Kingdom of Poland (Confess Poland) to the German Empire. Bessarabia is surrendered to Austria-Hungary. The Ottoman Empire has its territory in the Caucasus mountains returned.
I assume you think about the 'February Revolution'.
Then Michael has to - somehow - overcome the provisional goverments aims to continue the war at the ententes side WITH keeping the already negotiated russian gains of the Dardanelles, the Bosporus and the Caicasus after victory. ... No easy task. The provisional goverment decided together with the Petrograd Soviet in a common declaration to keep on with the war or at least not to conclude a separate peace with the CP.
Maybe he ... comes to some terms with the Petrograd Soviet ? ... as kind of a "peoples Tsar ? ... like 'Roi citoyen' Louis-Philippe in France ?
A public statement, that he wants to end the war ASAP, as long as it doesn't cost ethnical/majority russian country could help then.
However. At that moment the germans haven't taken Riga yet and the russians still occupy the Bukowina and parts of eastern Galicia - and btw the CP forces are occupying the Danube-delta (wee part of Bessarabia already ;-)).
And the germans would most likely be VERY happy to comply to an armistice with Russia dropping out of the war, to redirect theit forces against the western entente-parts as early as possible.
Therefore IMO german demands wouldn't extend too far into the Baltics, Lithunia, maybe with the Riga-region and including the Vilnius-region, maybe the estonian isles too as a 'Baltic dutchy' of some kind, german controlled ofc.
Congress-Poland with all of galicia as a "independant" Kingdom with the "Austro-polish" solution, transforming A-H into a trialist A-H-P empire. under heavy control of germany esp. economically.
Romania might be restored - without all of the Dobruscha, ceased to Bulgaria and also tightly bound to the CP, maybe with a new King of habsburgian or hohenzollerian origin (some side-line), and some adjustments on its hungarian border.
Serbia will be reduced to the size of the former Principality of Serbia - without the Kosovo - as an nominally independent state as well, a concession to the russians.
Bulgaria gets as said all of the Dobrusch and former serbian Macedonia.
The Ottomans get their pre-war borders in the Caucasus, maybe the region around Batumi as well. Being still heavily under pressure by the Brits they would IMO comply to this "limited" gains there. However, a russian withdrawel from persian Azerbaidjan might give them also some ... further outlook ;-) in the region.
As the fighting on the macedonian front is still going on, there isn't much more to be said about Greece, Bulgaria and the Ottomans there at this point.
That's how a peace of ... Pinsk could look about under these circumstances.