I see China's approach as more the DI_EFIL areas, than militarily going into Afghanistan:
- Diplomatic: curry Taliban favor by being their first and best friend on the UNSC, preventing or blunting future UN actions (e.g. sanctions, BOG observers) that are sure to follow a harsh Taliban regime
- Informational: assist the Taliban in painting the US/FVEY in a poor light wherever possible; present China as a "good guy" and a friend to the Muslim world, as a way to deflect Uighur criticism
- Economic: BRI, resource extraction, and related trade partnerships and economic initiatives; possibly narcotics related, too, as we know China is a major origin of fentanyl
- Financial: provide much needed investment money when Europe, global banks, and int'l institutions (e.g. IMF) might shun the Taliban; China may attach certain strings to these financial levers, but they can't be too overpowering or the Taliban will get financing from private Arabian Peninsula backers; but the Taliban are likely to take whatever investment funding they can get (and maybe pay it back or not)
- Intelligence: Chinese intel services will no doubt be active in Afghanistan, and China may arrange for intel-sharing with the Taliban in a quid pro quo arrangement if China perceives the juice is worth the squeeze
- Law Enforcement: China's model is a mix between Xinjiang and the "Smart City" - which is partly economic (building infrastructure), partly financial (if given on a loan or credit), partly intel (data collection), and partly LE. China may also offer to help the Taliban reconstitute some sort of border control on its various land borders, because border control can be a way for China to gain access to Pakistan, Iran, and Central Asia
I don't see China putting troops on the ground, but it's possible. China has been known to use forced labor in the past (which China deems expendable), and/or go the route of private security contractors like a Chinese version of Vagner. China can also just co-opt the Taliban and pay the Taliban for security at BRI locations. That's probably the first and easiest route, which only costs money, is the fastest option, will be the most acceptable to the Taliban, and has the least logistics tail.
TL;DR: Follow the (Chinese) money