According to Apple, when your AirPods are charging and within Bluetooth range of a Wi-Fi-connected iPhone, iPad, or Mac, software updates are immediately sent to them. If the most recent firmware isn't already installed on your AirPods, you may attempt updating them manually by doing the following:
Step 1: Make sure your iPhone, iPad, or Mac is linked to Wi-Fi and that your AirPods are within Bluetooth range of the device.
Step 2: The second step is to put your AirPods in their charging case and shut the cover.
Step 3: Attach the charging cord to a USB port or power charger and insert it into your AirPods charging case.
Step 4: Wait 30 minutes for the firmware upgrade to finish while keeping the charging case lid closed.
Step 5: Lift the cover and put your AirPods to use. Next, verify the upgrade by looking at the firmware version.
Apple advises restarting your AirPods and trying the update again if it hasn't happened yet.