I don't think that would've worked for the LWP - or, depending on the timeline or edition, any other iteration of the Polish Armed Forces. By the early 1980s the baby boomers peaked in militarly availability for conscription. After that, conscription cohorts shrunk massively by about 18 % for the male population.
Diagram 1:
https://upload.wikimedia.org/wikiped...yramid.svg.png
In combination with the shrinking defense budget and the general detente of the second half of the 1980s, that was the reason, why the LWP decided to downsize the 7th Sea Landing Division and the 6th Airborne Division down to brigade formations in 1986. Ten years later, the Polish economy wouldn't have fared better, because Eastern Bloc austerity and lack of reforms would've meant loosing even more edge against the West as well as the Tiger States of Asia.
While cohorts were rising in strength in the late 1980s again and reaching early 1980s levels by 1990, it makes little sense putting these "surplus" conscripts into specialized brigades to enlarge them into divisions. The coastal brigade had been shifted to coastal defense, loosing half of its artillery as well as its tanks in 1989. The unit was now a light infantry battalion tasked with guarding the Polish coasts. That is not a troop type that would make any sense adding more to, when asked by the Kremlin to muster banners and send forces to the China theater.
It works even less for the airborne brigade, since even during its time as a division it was never structured in regiments, like Soviet VDV division, but had four battalions. Downsizing to brigade level mostly meant activating an air-defense battalion, but not loosing any battalions in the process. In essence, there never were more airborne forces available, the label was simply changed to a better fit.
What Poland most likely would muster for the Chine theater is armored and mechanized forces as well as security troops to guard rear areas. While Poland had one of the best Warsaw Pact armies, its technological standard was still behind the peak of what the Soviet Army could muster. Few T-72s would be available during a surge in the 1990s, with most deployed in active units and only few available from schools and depots. That would largely leave T-54 and T-55, including a few upgraded ones, available for new units. The problem looks similar when looking at IFVs, APCs and SPGs: Poland had few surpluses here and lacked updates, meaning older models would have to be used for new units. In case of SPGs the consequences would be even more extreme: No surpluses meant towed pieces were the only available option, air-defense options would look even worse, with insufficient quantities even for some active divisions.
In the end, forming new divisions for the Chinese theater would mean pilfering active divisions to meet Soviet standards or sending divisions that would be lacking basic combined arms capabilities. Likely a mix would've be found, e. g. one division with prime equipment, two sub-par divisions and several independent security brigades consisting solely of light infantry forces.