Yes a 2 year old should still be in diapers if they are not potty trained.
There's no age limit to wearing diapers and there's no age at which a child must be potty trained by.
All children are different and will potty train at different ages and forcing potty training will just make it worse and harder for the potty training to happen.
If you try to potty train your 2 year old and they refuse to use the toilet then just keep the 2 year old in diapers and try again when they are 3 years old.
I would not be worried about the potty training until the child's 4th birthday and then if they are nearing 5 years old and not potty trained then the issue should be forced.
But it's normal for a 2 year old to not be potty trained and be wearing diapers.
Lots of 2 year olds wear diapers full time and there's nothing wrong with that.
Kids potty train between the ages of 18 months to 3 years old and some kids don't potty train until 4 years old which is okay as well.