i paired my ipods with tv. how do i adjust volume

The double tap on the side of the AirPod earpiece invokes Siri when used with supported devices so you can ask her to do the things you want like alter the volume. There is no slider or any other way to control volume directly on the AirPods.

Volume control as such would need to be done from the device the Airpods are connected to.

They do work with BT compatible devices, but as they don't actually have any buttons or surface space for controls not sure where a volume slider or buttons could be located on them.

You can read here for more:

Learn more about your AirPods with charging case - Apple Support

Also how would the Airpods know you want to lower or raise volume from a double tap?

With your TV's remote.

Unless specifically supported by your TV (don't know any that do) Siri voice commands for things like volume adjustment will not work.