The phone has 6 GB of RAM for your apps. This is a lot even for the more demanding users. You can even capture video in high definition. The internal memory capacity tells you how much space you will have for your files. If your phone's internal storage is less than 1GB , you will only get enough space for the bare minimum needed to run the phone. You will be able to upload a few contacts and calendar events. A larger flash memory with a 16GB capacity is the baseline if you want your phone to be "smart" in the true sense of the word. If you buy a phone with 32 or 64GB, you may not even need an extra memory card. 128GB or more allows you to store a week worth of movies.
The Xiaomi Mi 9T Pro LTE 128GB Red features a camera with a 48 Mpx image resolution. This means the device is suitable for taking high-resolution pictures you can crop and edit later on. The front side has a camera with a 20 Mpx image resolution.