@pwog12 My advice is find a different hike.  Mt Whitney is now on everyone's
bucket list and is way too over-subscribed just because it is is "the highest".  It is spectacular and if you do really want to go up there I would plan a longer trip and go from the back (4 to 7 days depending) but that does involve a could of creek crossings which you need to be prepared for.  This avoids the lottery and the wag bag issue (you must pack out your poo) unless you exit via Whitney Portal for which you need a special permit and use a wag bag if you must.  It also makes a better trip if you can't summit Whitney due to the weather.   I probably wouldn't do this as your first trip but summer 2021 is a long way off assuming we can safely get on with things.

As to gear, if there a lot of snow you will need crampons and an ice axe and know how to use them.  If there is some snow then hiking poles and microspikes will do and if there is little or no snow regular hiking gear is all the is required.  No climbing gear is required unless you plan to take the mountaineers route.  For clothing you need to plan for sun, wind and thunderstorms.  For camping you need to be prepared for 30F or lower at night and afternoon thunder storms which may prevent you from summiting and possibly some hail and rain.  If you do go via the back side you may need to plan on some mosquito abatement.

As far as getting prepared, unless you have health problems just being in reasonable shape and being used to carrying your gear including supplies comfortably in the footwear and socks that you will use for the sort of mileage you expect to do will get you there but also hiking hills will be better.  Mt Diablo is a ~3000ft ascent local to you...maybe next spring?   You can do more of course.  Good aerobic fitness and warm up and cool down stretching exercises can useful as can core and leg strengthening exercises.   When you go you need to plan on a day or two to acclimatize before hand.  Spending the night a Horseshoe meadow campground (~10,000ft) is a good way to do that. You can drive there. Also be aware of the symptoms of altitude sickness which if you are going to get it badly generally starts at around 8000ft and the best cure is immediately descending.  Ibuprofen is useful for mild symptoms and there is a prescription drug, Diamox that can also help.  Look it up and ask your MD about it.