Hello, take OPPO R9S mobile phone as an example, and the specific methods are as follows:

First, turn on the phone and click the "Settings" icon on the desktop.

2. After entering the drop-down menu, find the column "About Mobile Phone" and click Enter.

Third, click the "version number" column 7 times at the entry point.

4. Then return to the setting interface and select the "Other Settings" option.

5. Find the "developer option" after entering, and enter the engineering mode of the mobile phone after entering.