It has an 18 cert for a reason. It's still full of kids anyway, you hear them constantly when playing the online version. There's also constant swearing if your volume is turned up.
There's topless women dotted around certain venues such as the pole dancing club and the playboy mansion, sometimes a beach.
The prostitutes are available to get into your vehicle at night time, and all you see is a head bobbing up and down from outside the car window and some silly noises. It's animated graphics so hardly realistic.
It's violent. You can shoot people in the face at point blank range for instance.
There's also games where you can shoot robots or animals in the same fashion.
Minecraft is violent too as it mostly revolves around killing sprees and destruction, and a Roblox is another matter entirely. Even with all the parental lockdowns there's the chat bubble feature and little rooms your kids can go off into with other players.
As another poster said, it has some apt political themes, and great humour in the features.
But there's plenty of other car racing games suitable for kids than GTA. Including 'open world' style racing similar to GTA, but without the adult content.
Your husband hasn't played it if he thinks it's suitable for an 11 year old.
More than anything, it's annoying hearing kids in the background, shouting usually, being engaged in conversation with adult men.