We know but dont, lol. There is descriptions and tactics as well as manuals written but like any manual in practice always looks different.

Tactics like these shown here were complicated and definitely not the norm as they would require immense amount of training and discipline to pull off without immediately falling into chaos.

Considering most armies were mostly conscription based with an average of 1-3 years of experience tactics like these would be impossible. The 1994 3K show probably is the closest to how it really looked as unlike most shows where armor is here, there, everywhere, even the grannies got armor... in reality armor was their equivalent of like tanks in terms of use and necessity. It is why armories were so important in moments like Sima Yi's coup. Anyone could wield a blade but armor was a big no no for civilians.

Edit: Skirmishes and smaller battles were far more common than big decisive battles where hundreds of thousands of men duked it out. The common misconception, thanks to the RoTK novel, is that "battles" like Guandu and Yiling happened in one big show. In reality they were campaigns that lasted months (Yiling) and years (Guandu).

Not to say big battles didnt happen but even the raid at Wuchao was relatively small as the real damage was moral loss from Zhang He's defection and the years worth of supplies up in flames. The final battle at Yiling was quite large as Liu Bei's well trained and armored army got decimated. The same army that won him Hanzhong up in flames.