Vivo X90 PRO 5G (12/256GB) smartphone, as product details and specifications can change over time. However, I can provide you with a general outline of what you might expect in a high-end smartphone:

1. 5G Connectivity: The "5G" in the name indicates that the phone is capable of connecting to 5G networks, providing faster data speeds and improved network performance.

2. Storage: The "12/256GB" likely refers to the RAM and internal storage capacity. In this case, it suggests that the phone has 12 gigabytes (GB) of RAM, which contributes to smooth multitasking, and 256 gigabytes of internal storage for apps, files, and media.

3. Camera System: High-end smartphones typically feature advanced camera systems. Look for details on the megapixel count, camera features, and any innovative technologies that enhance photography and videography.

4. Display: Expect a high-quality display, possibly with an AMOLED or similar technology, providing vibrant colors and deep blacks. The screen size and resolution are essential factors for a rich viewing experience.

5. Processor: High-performance smartphones are equipped with powerful processors for efficient operation and smooth performance. Check for details on the processor brand and model.

6. Battery Capacity: A large battery capacity ensures longer usage between charges. Fast charging capabilities may also be included for quick replenishment.

7. Operating System: The phone is likely to run on the latest version of Android or a custom user interface developed by Vivo.

8. Design and Build: High-end smartphones often feature premium materials, slim profiles, and modern design aesthetics.

9. Biometric Security: Look for advanced security features such as in-display fingerprint sensors or facial recognition for unlocking the device.