how to ajust the aperture of the i2 fpv camera??

You cant....

It's a fixed FPV camera with auto exposure so you can see what's in front of you. The FPV camera isn't meant to be used for stills and video recording, so making those kinds of adjustments are not necessary.

It would be nice to add the ability to override the autoexposure as it can get it wrong - particularly if the sun is in front and there's another source of strong/bright reflections such as cloud or snow. Could you pass it through to the R&D dept for consideration for the future!

the fpc camera is absolutely useless in bright sunlight and snow...dji, we need an nd filter