UCAS extra question

i have 2 offers for BBB at the same uni for different courses which are my only offers however there is a uni i would prefer to go to in ucas extra for AAA. Can I accept one of my offers in May and then reject it after a levels (contingent on how i felt exams went) to then apply in extra for the AAA course? If I get lower than AAA and I miss the offer will the BBB university discriminate against me if I reapply to them by clearing?

1) Why don't you want either if the offers you have?
2) Is the course at the other Uni still accepting applications (phone them and ask)?

Ucas extra is only up until 4/7/24
https://www.ucas.com/undergraduate/after-you-apply/types-offer/extra-choices
If you did not use all your choices in your initial application, you don't need to use Extra, you can just sign in to your application and add another choice, as long as it’s before 30 June, and you’ve not accepted or declined any offers.
If you don’t hold any offers after 5 July, you will be able to add an additional choice using Clearing.
After which, is clearing.
https://www.ucas.com/undergraduate/clearing-and-results-day/what-clearing#:~:text=Clearing%20is%20how%20unis%20and%20colleges%20fill%20any%20places%20they,re%20applying%20after%2030%20June
With clearing, there is no guarantee that course would be available.

I gather from previous years and from family members that have gone through clearing that my courses which I currently hold offers for would most likely be in clearing. Also these courses are also on UCAS extra. Do courses which don't get filled on on Extra usually go into clearing? This could be the same with the AAA course I was looking at although that university doesn't usually go into clearing

If a university doesnt fill all its applicants through extra it is likely they will then look to fill them through clearing. However universities make many times more offers than places as they know most students will go elsewhere or not reach their grades.
Whether you use extra or clearing you will need to be holding no offers ie been rejected by or rejected ALL your offers. Extra is better to use as if you get rejected you can apply elsewhere and also you are able to get accommodation and the process isnt as rushed.
Sometimes a university you reject will take you back if you dont have an offer elsewhere. If you dont intend going there this is pointless anyway.