First, I'll go to youtube, hoping that someone gave a talk about whatever tech it is, these are good because talks often distill the high level architecture into a 45 minute presentation and it gives a decent starting point to understanding the minutia.
However, what often ends up happening is I see lots of videos and pick up nearly nothing (as most are not talks, they are mostly indian people making course materials).
After I fail to do the youtube thing, I usually go to the quickstart guides, or copying example code and messing with whatever it is, stepping through each item of the code or futzing the configuration to try to make it do weird things, reading up documentation on each config key.
After that I start branching out into other areas, how do I make whatever it is much different? if it's software, how do I scale it, what are the individual components- if it's a library; what else does it support etc;
I very rarely read an entire manual, but after back-and-forthing a bunch of times with experimentation I have usually read a huge chunk of the manual.
However where this really fell down was with kubernetes, as a concept it's very large and hard to break down into smaller sub-components, and when you're testing the entire thing at once it feels like "magic inside" which is not ideal for my method of experimenting (try/break/fix/repeat) as too much breaks at once.