Hello I am in grade 11^th. I’m sorry if you find my question a little erratic.

I am planning for engineering. What do you deem to be better, doing engineering from IIT or some foreign institue such as maybe the University of Pennsylvania, US?

As you know IIT's are premier institute for engineering, so there is no doubt about that. But both options have their own pros and cons.
At IIT's, the competition you will find is unbeatable to any other university.
Foreign institute, if you get into top colleges/ universities, then you can choose as their research level and other facilities are impeccable.
If you are research oriented go for foreign institutes but if you are looking for job immediately after your graduation for IIT's.