This is a huge topic. It's 4:26am local time right now so I won't write too much.
Sticking to the current theme, China's BVR technology has been proven to be astonishingly successful in recent events. This is an area the West always claimed absolute superiority against. MBDA's Meteor was the best medium-range AAM field by the Western world. More capable than any Amraam variant currently fielded. But Indian failed at achieving air supremacy. PAF J-10s came out superior
J-10s are the lowest-tier fighters in the PLAAF. J-15s, J-16s, which have enormously more powerful radars and sensors will be an even bigger of a nightmare for Indians. Non-the-less, the J-10s and JF-17s performed exceptionally against a much larger force. So did its datalink system, and synergy with the rest of Pakistani Chinese supplied systems in the battlefield.
AIr to air missiles is a field China definitely has a lead over the US currently. When the US finally fields a next gen AAM to replace their aging AMRAAM's, China will move onto something else. It'll be too late.
China's R&D resources and talents dwafs the US.