Hi Koby, I can only relay my experience transitioning from System Administration to Platform Engineering so please take what I say with due skepticism;
Firstly, it's very doable, provided you are aware from the get go that it's more of an evolution than a transition.
When I was a sysadmin, it was 2006, "DevOps" hadn't been invented yet and web2.0 was the new hotness. By the time I was a Platform Engineer™️ ( 😉 ) we were post container-revolution, "digital transformation" was no longer a buzzword and Heroku had already been around for a long long while.
For me it was a long journey from one perspective to the other. The biggest shift in my thinking has been interfaces. From my personal perspective, a platform is really only as good as it's interface, since that is what your Developers will be interacting with.
In my experience as a sysadmin, I was mostly reacting to things, or at least trying to proactively limit how much reacting I had to do. I wasn't really building the tools I needed, and I wasn't building tools designed to be used by people not doing the same thing I was doing.
For me designing and building "platforms" has largely been about thinking very hard about the way we expose the curated collection of tools, software and features to our developers so that they experience something cohesive and which supports their goals. Obviously theres a lot of nuance to that but for me it boils down mostly to that.
Yes, the tools of the trade change over time and there's always some new fancy thing people wanna use, be it a language or a framework or a whatever. But if you can keep thinking about how the tools you design and build are going to be used, and be useful, then i think you're well on the way.
Best of luck. hth