Yeah well… “giant” ants still aren’t lion sized. Or even cat size. Perhaps “oh wow that’s a big ant” big, but not actually that… big.
The fossils indicate that the males grew up to 3 centimetres (1.2 in) and the queens grew to 7 centimetres (2.8 in). It had a wingspan of about 16 centimetres (6.3 in).[7][8]
A lion sized ant would asphyxiate rather quickly. Breathing through spiracles/tracheae doesn’t scale well.
But there were giant ants during the Eocene
https://en.wikipedia.org/wiki/Titanomyrma
For the sake of argument, let’s assume a hyper-rich oxygen environment.
Yeah well… “giant” ants still aren’t lion sized. Or even cat size. Perhaps “oh wow that’s a big ant” big, but not actually that… big.