Can you charge Oculus Quest 2 with a phone charger? Yes you can. However, the charging speed may vary due to the charger type and USB C cord quality.
In order to keep your Quest 2 in good working condition, it’s recommended to only charge the headset with the charger included in the box. Do not use the headset while charging.
Regardless of the charger is 5V, 9V, or higher voltage. The headset will only draw the power it’s designed to do. Do not use a poor charger with inconsistent voltage or amperage drop.