It's about as easy as it gets, don't worry

It's not that hard, to be honest, just be careful and you'll be fine...
 

If you want to get an idea of what's involved, I don't see manual for 30xx series yet but manual available online for the hybrid kits for the 20xx series and it will be similar.  If it gives you too much anxiety to attempt, you could get on the notify list for the factory hybrid card and I'm sure sell the one you have now without any problem when you're ready!   If you read buried deep in warranty you'll find a passage that states damage from 3rd party accessories NOT approved by EVGA isn't covered, also in the hybrid manual for the 20xx series there's a section about leaving the thermal pads in place in case you need to RMA ( Note: If you do RMA, I believe you have to restore the card to original spec! ); if it's EVGA's hybrid kit you're good on warranty.

Perfect info!!! Thank you so much for the in-depth reply. I did sign up for the notify of the hybrid card as well just in case.

I just installed hybrid Kit for my 30090 FTW3. It seems like there isnt much change with temp

I got notified for my 3090 FTW3 cooler kit 12/10 and ordered.  Received today.  Just installed. So much quieter.  Just like I was back with my 2080ti Hybrid.
 
Easy install.  Biggest challenge was removing all the old putty.  Make sure you have High % Isopropyl on hand and some lint free cloths. 
 
Handful of tips:
 

• When removing the original GPU bracket, Hold onto it.  It is terribly sproingy.
• When removing the backplate screws.  There is one hiding under the EVGA warranty tamper label.
• Does take a bit of force to get the original heatsink off.  Slow gentle pressure is your friend.  Do not twist.
• Have some compressed air to blow little fribbles of putty away.

One oddity I noticed.  When setting the RGB colors on the cooler.  The Red and Green channels are switched on mine.  I do not have the RGB on the fans hooked up so can not really tell if that is being affected the same way.
 
Oh and I am noticing about 15 degrees cooler when running under load with a much lower noise factor.

It’s not at all hard to do, but if I were going to this effort, I would think seriously about a proper water cooling system.  With flexible tubing, it really isn’t much additional effort and will give much better results.