Going from enlisted to OCS, is this a process where you have to prepare and submit everything yourself?

"prepare and submit everything yourself" for what? - it would help if you gave more information about the topic you are asking about.

Assuming you are asking how to apply to the OCS program, your local Army recruiter is the place to start*. Before you can apply though, you'll need approval from your chain-of-command. The one thing that stands out is that you must be on track to finish a bachelor's degree within one year of enrolling in OCS.

If you don't have a degree, or aren't close to completing one, then Green to Gold* (G2G) is a route you can apply to.

If eligible, OCS will be quicker - classes run throughout the year and it's a 12 week process.
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* https://www.goarmy.com/careers-and-jobs/find-your-path/army-officers/ocs.html
* https://armyrotc.army.mil/green-to-gold/

You need to start with your rnco and talk to your commander. You RNCO should be able to tell you if you qualify or not, and you will need the CO's endorsement to apply. A lot of it will be on you, letters of recommendation as high up as possible, and they used to require an essay on why you want to Commission. I don't know if they do in person boards these days or not.

OCS isn't fun. I didn't find it particularly hard, but TAC Officers aren't Drills and make it a real pain in the ass.

You commenters in the other branches are too easy ha ha! In the Coast Guard going from enlisted to officer means showing that you possess "officer-like qualities". The first of these qualities is the ability to find out what message traffic, manual, or other official directive contains the information and procedures regarding how to apply for OCS. All interservice kidding aside, I wish you the best SGT.

First of all. If you want to risk your career go US Army officer. If you want a career and you know you want a career in the military as an officer, go any other branch but. I made the unfortunate mistake of chosing the US Army to become an officer in. My family ended up paying for it. Remember Tillman? well the only reason you don't hear about others that have lost big is because the news media refused to print it because we are not celebrities. I have been fighting an illegal separation going on 17 years now, and even after the court rulling, ABCMR STILL refuses to fix anything. Go officer in any other branch. At least those officers are honorable.
Second, when I left the US Air Force to take my commission in the US Army a recruiter did pretty much everything. I had lose about 35 pounds because USAF standards were less stringent the US Army standards. I did so in a two month period - surprised the recruiter, but showed him how determined I was to start my career. He put me through and got me all set up. I would have done it all myself if I had to - check with your recruiter first though.

Go the to bottom of the page and begin a discussion with a recruiter on the application process.
You need to get in a position to tell your Commander what you intend to do and what you need him/her to do. If you find yourself asking your commander what you need to do then you are on the wrong foot. https://www.goarmy.com/careers-and-jobs/find-your-path/army-officers/ocs.html

Form the Army website: "You must be a U.S. citizen and have your bachelor’s degree by the time you are commissioned as an Officer. The general age requirement is between 19 and 32. You also have to be eligible for a secret security clearance. If you’re current military, you can’t have more than six years of active service before joining OCS. To learn more about OCS requirements and how to apply, civilians can talk to a recruiter, while active-duty enlisted, Army Reserve, and National Guard Soldiers can talk to their commanding Officer."

So start with talking to your commander.

You need to get hold of the OCS packet so you know what the battlefield looks like.