bblindcat97, actually Physics and Particles in Blender have hardly changed in years, and all the information in this course is still relevant.
The most changes in this area have been with the UI.
We do recommend learning with the version of Blender used in the course to eliminate the frustration of these UI changes to the software.
Remember you are learning 3D/CG, Blender is the software we choose, each version of Blender is a tool to assist in our learning.
Just because v4.x is the latest version of Blender, there is no rule that says you have to use it.
I know of many professional artists still using v3.0 and earlier, because they have no need to change version.
They are obviously comfortable with the version they use, and it does what they need it to do.
The reason the Physics and Particles systems have not changed is because the Blender developers have been working on the new Simulation nodes system.
We do have a new course called Particles: Introduction to Simulation Nodes which you may be interested in.
You may have seen a famous Donut tutorial on YouTube, and the many iterations of it, using each new version of Blender as they are released,
but the result is the same, it's still a Donut whatever the version.
Yep as Adrian said, no need to fear the Blender version. You can download the version that is used in the course and the knowledge still holds. You can watch both the new Simulation nodes course and the old physics and dynamics course and you'll just have more mastery of each topic.
This was recorded back when the fluid and smoke simulator were separate, so those really are quite different nowadays. The cloth, soft body, and rigid body systems are almost exactly the same. The reason I haven't done much with fluid physics recently is because it's a bit of a buggy area in Blender (specifically parts of the smoke sim) and longstanding issues haven't been addressed, so I don't really feel like taking a couple months to make a new course about the topic. That said, there's a lot of interest in fluid simulations still, so I do plan on making a course about liquids later this year.