With the DJI Googles Integra, there are 11 (Pair) corrective lenses included. From -8D, -7D, -6D, ... to +1D, +2D.
If your correction is one of these numbers, put the right lenses into the googles and you are good to go. Otherwise, if like me you are outside this range (I need +3,5D) then you need to order custom prescription lenses or use contact lenses like I do, works perfectly.

With the DJI Googles 2, you can adjust manually the correction, so I guess you can have -6,5D for exemple, but the range is also limited from -8D to +2D. If you are outside this range, the only solution is contact lenses.

Yes

No, the Explorer Combo includes the DJI Integra goggles, which do not have a dioptre adjustment.

You would have to take a package with DJI Goggles 2 (Pro View Combo), which will probably be more suitable for you.

It's best to research the difference between these two goggles online, there are numerous threads about them.