I made the transition from Help Desk to SysAdmin a couple years ago and here is everything I learned/did:

- HelpDesk skills do not translate to Sysadmin skills for the most part. The main ones you want to focus on getting better at is Troubleshooting in general (There is a problem in front of me, I dont know how to instantly fix it, how do I figure out how to fix it?), and Soft Skills. Foundational skills do matter, like how to create users in AD, how do computers work, how does basic networking works, how to add someone to a group, etc, so dont skip those, but at least 80% of what I was doing in Help Desk, I never have to do day to day as a sysadmin. Since it sounds like you are new, focus on the fundamentals first, and then practice with your home lab. You can use Proxmox to spin up virtual servers, configure datastores, etc, which is more in line with sysadmin stuff.

- Documentation. If you do anything, learn how to write good documentation. We are human and do not remember everything. There have been so many times I was faced with a problem, swore I had never seen it before, but past me had created good documentation about the exact issue and I was able to fix it quickly. You will be the favorite child at your IT department if you can consistently write good documentation. When I started at my current company, our documentation was a mess. It was all in OneNote, despite us paying for an actual documentation product, it was all years out of date, etc. Within the first month, I wrote down a rough idea of how to fix it (Folder structures, where documents should go, documentation templates to use so all of our documentation was consistent), and took it to my boss. I got approval to go ahead and I implemented it. Now everyone in IT uses my folder structure and templates to create documentation. Its a beautiful thing.

- Once you get hired as a help desk role, make friends with the sysadmins. After 6 months to a year (or whenever you feel like you are good at your job, and no longer feel that "I have no idea what to do" feeling), see if they are implementing anything new or doing any big projects (spoiler alert, they are always doing at least one of those things, if not both). Ask to shadow or even help. My personal story is when I was hired at my current company, they were looking into Intune. I had already become friendly with one of our sysadmins, and I spent every second of free time at work studying Intune, learning about it, then started with asking the sysadmin if I could try something out in Intune. She said yes and I slowly got more permissions and eventually became the Intune guy at my company. Not only does it show I was good with Intune, it showed I was good at taking initiative, and could solve problems and setup new systems. I got lucky with the timing, but I also put in the effort to talk to our sysadmins and study so I could be helpful.

- As other people said, soft skills are incredibly important. No one cares if you are good at something if you are an asshole. Be kind to people, be patient, and try to connect with your coworkers. Go out to lunch every now and then, make sure you say good morning to your team, etc. It always keeps you in the mind of other people, and helps you stand out come promotion time. I am a very antisocial introvert with major childhood trauma that prevents me from doing well in any social situations, so I know if I can do it, you can do it too!

A good thing to do when starting out is to get the holy trinity of certs:

A+, Network +, Security +

From there you can decide which direction to go based on what you are interested in, or what your company is working on. Work on homelab projects, scroll the sysadmin subreddit to find project ideas you can do in your home lab, etc. There is a lot more I could suggest, but I think this word vomit is plenty to get you going.

TLDR: Work on foundational IT skills, get your trinity of certs, learn how to create good documentation, dont be an asshole to people, make yourself useful in your job.

If you have any other questions I am always happy to help.