A single character model can have more polygons then a whole game back in the day. The textures are also way more detailed, animations are more fluid/realistic, etc.
This is why a lot of effort is being put into helping developers to make content faster with things like automatically generating large parts of levels/worlds (basically a developer puts in the important parts manually and some system fills in the rest) and automatically generating and animating humanoid models (MetaHuman), etc.
For example here is nice video about using MetaHuman with basically just a phone for face capture as input https://youtu.be/pnaKyc3mQVk?t=72
UE5 procedural generation stuff https://youtu.be/akIqVM0gh4w?t=435