We can always check the certifications or verification labels, such as the FCC ID required to use the device in the United States, or the HAC rating of the OnePlus smartphone in the device data.

Note: Regulatory labels may vary depending on the device model.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Settings
Step 2:  Tap on  About phone
Step 3:  Tap on  Regulatory labels
  1. Open the Settings
  2. Tap on About phone
  3. Tap on Regulatory labels

OnePlus Instructions