Not OP but in my experience people tend to have trouble comprehending systems of planetary gear sets.

Although modern automatics are probably a bit easier to understand than old ones, especially CVTs? As long as you're ok with "the computer just triggers this solenoid.." rather than understanding a big hydrualic computer.

Modern automatic transmissions are actually manual transmissions with a robot moving through the gears as far as I know. However, they do a bunch of stuff that I don't understand like pre-engage the next gear so the switch is faster -- I have no idea how that works

Yeah they sure are, they are manual transmissions with a solenoid controlled dual-clutch setup. One clutch engages the next gear as the first releases, there is no lost thrust as with a single clutch pedal, and you get to save all the weight of hauling around a huge valvebody and fluid and clutch bands.... Great stuff.

The Howstuffworks article is great. Have fun. https://auto.howstuffworks.com/dual-clutch-transmission.htm

> like pre-engage the next gear so the switch is faster -- I have no idea how that works

I think you're referring to dual-clutch transmissions: odd gears on one clutch, even gears on the other. So the transmission can switch from eg. gear 2 to 4 with the even-numbered clutch disengaged while transferring power through the odd-numbered clutch in gear 3. When it's time to move up to gear 4, one clutch is disengaged as the other is engaged, instead of having to leave a single clutch disengaged while the gear change happens.

I've found that building the Lego Technic Porsche 911 set from a couple years ago really helps a lot with understanding dual-clutch transmission systems. https://brickset.com/sets/42056-1/Porsche-911-GT3-RS