I started stupidly a TL about this exact topiclong ago, but I simply don't have the skill or time to make it as good as I wanted it to be, at least for now, anyway think about that gave me many ideas.
First I think Russia needs to not alineate Romania and prevent the Westernization process they had where they tried to re-romanize their language, using latin script and all that, it's possible they have to give up Bessarabia but at the same time they can get favourable deals and relationship, possibly using Bessarabia to appease Bulgaria taking all of Dobruja, Bulgaria being their strongest ally.
I find hard to have a complete compromise all over the Balkans that Russia can manage to achieve, especially with Greece and Bulgaria, maybe giving Dobruja and Macedonia(well you know which one) to Bulgaria would be enough for them? This strikes me as super idealistic and convenient to have Russia, by simply giving a backwater province make the Balkans work, but it sounds interesting nonetheless, anyway we have our fair share of nations Russia doesn't have to care about, like Croatia, Albania and Hungary and they don't have to compromise much and can just support their Orthodox powers. The Balkans would be basically be 4 Orthodox countries(Greece, Romania, Serbia-Yugoslavia and Bulgaria).
For Central Europe, Russia needs to appease of put down the Poles, I think they would need to carve out a smaller and totally homogenous Congress Poland(of course taking land with remotely any Eastern Slav for themselves) and use as a proxy against Germany and Austria. Otherwise, they would need to avoid the pale of settlement and allow Jews to spread all of over the Eurasian empire, possibly decreasing Polish population significantly and on the other side allowing some strong settlement in the region, especially urban areas.
Earlier railroads would allow for faster colonization, although I highly doubt they would retain Alaska, although on the other side I think they could aim for the Hawaii, even if just as a vassal state.
Hokkaido I'd argue can fall to Russian hands, although this still requires them to have their back not exposed(as it really requires war at this point in time) and play a very good diplomatic move, last thing they want is that people stop caring about Germany and start caring about them as a threat. Okinawa on that front seems excessive, at best some sort of vassal state but the English would hate it, as would everyone else.
Korea as a vassal is possible, but only in an economic sense and not politically so. For Manchuria I can't see it being directly annexed forever, even if Chinese weren't as numerous merely annexing this faraway territory won't stop the trend now, I can see them annex stuff north of Harbin or east of it, so the less populated but still valuable land to hold, the rest would be a Manchukuo like state, that would be prevented to be too Chinese by a mix of using the Koreans as workers or allowing them to settle the place while trying to prevent as much Chinese migration, and of course some sort of Manchurian identity could survive, although it would possibly lose the language.
Mongolia and Xinjiang would be vassals, although I imagine the Russian would either split the northern half of the later or annex it, but I imagine they prefer to would annex it, at least in the short term.
In Central Asia I can see Russians or East Slavs becoming the majority in Kazakhstan in the early 20th century, possibly relegating Kazakhs to south of the Balkhas Lake and to the Syr Darya river, making the Northern parts permanently Russian. Well they kinda were already OTL but this time it wouldn't require massive quick state controlled deportations but it would be more organic and stable.
In the Caucasus and Anatolia, Russia could create a Georgian and an Armenian state and try to first create some sort of stable border between the 2 and of course expanding their borders towards azerbaijan, only leaving oil reserves or just a direct corridor to Iran and a directer control of the Caspian sea, plus there weren't any minorites so far East. In Anatolia at this point some sort of Wilsonian Armenia and Eastern Pontus would be part of Armenia, although of course Georgia would get the Laz territory as far as it is feasible.
There's a probably a lot more to say, but this is getting lenghty lol.
