To keep within the borders the OP is discussing, Qing expansion would have to stop before the Kangxi Emperor defeats Galdan of the Dzungars in Mongolia in 1696 at the battle of Jao Modo. Failing to win here would leave the Inner Mongolian provinces and northwest China provinces less secure with probable higher grain prices and requirements for greater garrisons. The Dzungars would have control over Outer Mongolia and a stretch of southern Siberia in addition to Xinjiang and eastern Kazakhstan. They should be at least as well positioned as in OTL to later on intervene in Qinghai/Amdo/Kokonor province and Tibet proper.
The Dzungars have more mineral resources to mine, and may be able to purchase more western arms from Russian or EIC traders.
The Qing have less prestige and less of a "peace dividend", so could be worse off. On the other hand, they could stay militarily "fresher" if they have major battles every generation with the Dzungars with continually upgraded technology. Potentially, if that continues until the 1780s-90s, and first half of 19th century, instead of rejecting the MacCartney Embassy and British trade overtures, China might be in the market for British arms, potentially butterflying away the opium war, or delaying it.
If however failures in war against the Dzungars in the 1690s turn out to be catastrophic, maybe the end of Kangxi's reign turns into a downward spiral, with emboldened Dzungar invasions and revolts, disputed successions, and finally Russian invasions and western gunboat diplomacy by the middle of the 1700s, perhaps setting up China for partial Raj-ification by the later 1700s?
