To get the wide spread reforms that the OP wants, to setup for a stronger China down the road, i would suggest an earlier kick off of the Warlord Era, right after a stalemate/defeat in the First Sino-Japansee War. Better showing by Qing troops on land and sea (due to Prussian training), leading to little to no crippling indemnities but still the loss of Korea overlordship and Formosa, thus letting Imperial Japan stay on their crash course with Russia.
Except this time, the central government under Gong/Guangwu will be holding better cards from a more modernized prussian trained and LOYAL military (who overall fought well and didnt break and run like bitches like OTL), and can smash rebellious local warlords (who arent as well equipped as they would be 20 years down the line) and reactionary nobles into dust, thus clearing the way for needed future reforms. I'd have it where Prince Regents appeal to the people and get popular will on their side, offering a Constitutional Monarchy route of shared power. So it'll be a showdown with the trained Imperial Army + as much popular support as the Regent can muster up vs feudal reactionary Manchu/local nobles and angry not that well equipped warlords who want to do their own thing. Just have Li Hongzhang and a few other top dawgs decide to throw in with the Prince Regent (seeing the effectiveness of the Prussian trained troops being a key factor of their choice) and thus the biggest potential warlord is now fighting for the Regent, thereby bolstering their cause greatly, thus leading to a much shorter and less destructive Alt Chinese Civil War.
Have this Alt Chinese Civil War coincide with Russia and Japan fighting it out, as both sides believe now is their best chance to get more clay at China's expense as China cant do a thing to either of them during that time. Japan eventually wears Russia down as OTL, maybe doing a bit worse cuz they didnt get the war reparations from China like OTL. China spends this time swatting reactionary rebels while the people either support the regents reforms (Land reform perhaps?) or stay neutral and wait for the dust settle. In a stroke of luck (maybe ASB can toss out if so), USA decides to support the Qing by giving em investment support (USA wants to open up the Chinese market) and keeping the UK from supporting the rebels. UK follows suit in investing in China, hoping to keep it on friendly terms as a counterbalance to Russia (The Great Game in Central Asia) and Japan. The Alt Chinese Civil War is brutal but much shorter with around say 10-30mil casualties on all sides.
China comes out of the Alt Civil War more centralized, unified, and cohesive than its OTL self, while able to carry out some reforms now that the back of the reactionary nobility is broken. Tsarist Russia is exhausted as OTL and goes through their troubles. Imperial Japan has "won" but is way more exhausted than OTL due to lack of 1st SJW war reparations and a longer Russo Jap War. Japanese economy is likely in freefall and they cant try to punk China for war blood money due to their own exhaustion and the US/UK telling em to chill the fuck out.
During the leadup to the Great War, China plays on all sides. Promising to open a 2nd front against Russia and against Entente asian colonial possessions to keep German technical aid flowing in. To promising to NOT open a 2nd front against Russia and the Entente as long as UK/USA keep investing in China and helping it modernize.
I think the above is a good canvass to work with for what the OP wants. China is in supremely great position to take advantage of the post WWI world order, along with a economically crippled Japan limping along with delusions of granduer.