There are a number of apps that use AI and can be used on smartphones. Here are a few examples:
These are just a few examples, and there are many other apps that use AI in various ways on smartphones.
The prediction of the next typed word in the smartphone keyboard app also uses basic (or advanced, depending on the brand/model) AI functionality like recursive neural networks, LSTM etc. So, since AI is now an umbrella term for anything that makes predictions based on some features and statistics, a lot of applications can be considered AI, not just the hyped ones that understand language and produce texts or fancy images.
Play Store is full of AI-Enabled apps, kindly mention "For which purpose" like healthcare, writing, e-commerce, etc to get valuable suggestions.