iOS update 12.1 and later changed the location of SIM Applications and placed it in a more logical location but still under settings. Go to Settings -> Mobile Data and there you will find the SIM Applications.
It used to be under Settings-> Phone but has now been moved to Settings-> Mobile Data.
This change started with iOS 12.1 and is still present in iOS 13 and 14. This is where you can get your SIM Toolkit menu option similar to that on Android phones.
It is significant to note that it is also where you can get your iPhone APN settings. It is under Mobile Data Networks and you can use them to access the internet as it is unique to your carrier/ mobile service provider. Network selection and SIM PIN are also located here.