Short answer is NO, IoT is really a concept about "things" communicating (usually over the internet) with other "things", by this definition a phone can just as easily be a thing as a raspberry PI, or a PC.
IoT as a concept is device agnostic.
From an Android Studio point of view, adding IoT support means that common protocols and support libraries such as MQTT will be added to the project so that you can make use of them in your application.
If you have a need to implement an IoT Connection and the rest of your code or logic can be executed from the phone or whatever the device is, then go for it, congratulations, your "Phone" is now a "Thing" that can be connected.
Is it still IoT? That becomes a subjective discussion, but usually an irrelevant one. From a purists point of view IoT implies Device-Device connections, where each device knows how to perform specific operations and either does this on a scheduled or triggered basis, or after receiving a command from another device. So an IoT solution will usually involve a lot of satellite devices performing discrete operations or relaying telemetry and there will be separate processes or entities that coordinate between these "things"
In a practical sense, you will find that many IoT implementations will involve micro-controller devices like Arduino or mini-pc / compute boards like Raspberry Pi as they provide a hardware platform that simplifies how we can get our logical code base (software platform) into a specific environment that can interface with hardware to collect telemetry about the physical world or that can otherwise interact with it. But that is only a subset of possible applications of IoT.