After just joining the Reserves, can I change my contract to pursue OCS? If not, could I drop a packet once I’m done with AIT?

You can attempt to renegotiate your contract, but that mostly applies to erroneous enlistments where the recruit is found unqualified for the original contract, or the original training path was invalid.
Or you can complete AIT and simply volunteer for OCS.
You just have to start OCS before your 35th birthday.

FWIW, you're not "stupid" for enlisting with a degree, 7-15% of new enlistees come in with a degree, it's on the higher end for the Air Force and SF in the Army, and for the reserve components where graduates who have already started a civilian career are just looking for a way to serve close to home.

What would be stupid is to enter and serve in the military with no regard to what you actually want to do in the military.

Can you change your contact? I don't know.
What I will advise you to do is start an OCS packet now and at least investigate and consider ROTC. You could work on a masters and earn a commission through ROTC in less than 2 years while still in your reserve unit. At your age you need to have all the information as you're nearing commissioning cut offs.

Best of luck

Do you know that there are separate recruiters for Officers and enlisted? Recruiters also have monthly quotas to send people to entry level training. Enlisted recruiters don't get credit if you switch tracks halfway through and decide to go OCS. With that all said, what did the officer recruiter say when you spoke to them? If you want to go enlisted do it. If you want to commission do it. Will being enlisted first make you a better officer? Maybe. Will you be able to be a good officer without going enlisted first? Yes, of course. Some of the best and some of the worst officers I have ever interacted with were prior enlisted. It isn't automatic. You need to stop talking to people who served and start talking to the folks in the system. Talk to an Officer recruiter and go over your options.

Playing a little devil's advocate here and I'm of the assumption you've enlisted in the Army Reserves.
If you decide to go the OCS route, you'll still have to go through Initial Entry Training and Advanced Individual Training too. Mainly because you'll have to apply for Federal OCS and that will take time (up to almost a year) for the application and selection process to be completed.

Now if you are in the Guard, you have three OCS options. You'll still have to do at least IET to enter State OCS. There are two State paths, one is a 16 month class offered in each state, the other is an accelerated State OCS program in Alabama. You also have the Federal OCS as the other option. The State programs start in March of each year. The Alabama program starts at the same time but you'll need to talk with the OCS staff for the best class startup information. It may not be offered any more due to budget constraints.

Here's how this is probably going to play out:

I don't know if you can submit an OCS packet prior to you shipping out. Very unlikely because these are processes that have schedules that likely will not start, stop, and select you prior to your shipping out. You would have to be straight up selected for OCS prior to shipping to cause something to change the contract. You'd also need an entirely different medical exam.

So you are obligated to follow through on the contract you signed. Who knows, maybe you can submit a packet prior to you shipping out and you get selected while you are in the middle of your enlisted training. Probably not. I don't actually know.

This is the most likely scenario:

Now......... once you are out and a fully qualified USAR soldier you are going to be free to apply for OCS at your leisure. Being a reservist you have such an astronomical advantage over an active duty SPC trying to do the same thing.

However, the process is difference when you are a soldier verses a civilian coming in off the street. Your letters of references are going to have to come from your chain of command, you'll have to jump through hoops of your immediate chain of command from your squad leader, your platoon SGT, to your Platoon Leader or 1SG and finally getting face time with your Company CO and then probably need your Battalion CO OK on the process as well.

A civilian wouldn't need to do that. Then as well, everything do did the moment you stepped on the bus to Basic Training up till the time of application will be scrutinized. If only for the fact they Army will have visibility on you. Where as, if you were a civilian, you could flip your boss off and key his car and that probably wouldn't be included in the application.

However, as a reservist you have all the time in the world to deal with jumping through the hoops on your own time without having to play the chain of command game with a squad leader trying to get things completed and signed that are critical to the packet process.

It's not the end of the world. You'll still commission 10 years prior to myself and have a chance at reaching Full CO. If you are half way competent the USAR will be more than eager to bring you into the officer ranks.

Hopefully, you may expect a response from MSG (Join to see) or SFC (Join to see). Their responses are always well informed.

Ultimately, the decision should align with your career goals and aspirations within the military.