Hey there,
Apologies for the noob question, but poking around the Character Builder and noticed that there does not appear to be direct support for taking say 3 levels of Druid, then 3 Wizard, and then Prestige Classing to Mystic Theurge…
Are Prestige Classes no longer a thing in PF2E?
A number of prestige classes were converted to Archetypes in 2e, however prestige classes were done away with in PF2e.
It should also be noted that in 2 edition of pathfinder you stick with the class you pick at character creation, the base classes do have archetypes you can pick as well but if your group isn’t running free archetype then you will have to spend your class feats you pick up on the archetype feats instead.
Multiclassing is done via class feats. You’re required to take 3 multiclass feats (the dedication plus two other multiclassing class feats) before you can take a second dedication. Your class is ALWAYS your primary class.
Then, archetypes fill the role of prestige classes in PF1E/D&D3E/3.5.
There’s also a variant rule that Paizo calls “dual-class characters” but which functions more like ‘gestalt’ characters did in D&D 3.5. Two classes are developed in parallel rather than adding levels from each.
I don’t think many GMs use the dual-class variant, but some use the variant to add one free archetype from which to develop ‘cross class’ features.
Multiclassing can be fun, but it can also result in builds that break the game for those who don’t do it. It happened is 3.5 and happens in 5e.
Thank you all for the input and clarifications.
I’ll go examine the various options and see what setup I can put together which would allow a single character to make the widest array of magical items possible … 
Thanks again for the guidance and clarity!
Lady A
Thank you for drawing my attention to this variant rule at least.
I’ll consider it to see if I find it too powerful, but at least I know it exists now
Curious additional question: I have now stumbled across the options for “Magaambyan Branch Advancement” from the Kindled Magic expansion.
Does this system of “studying on the side with perks arising from this endeavour” effectively count as pursuing a “free Archteype” - or is this somehow considered a “standard” feature. I see it’s considered to be “useful benefits to improve your characters capabilities”
Previously when I was looking at the Magaambyan Attendant Dedication Feat I was assuming this replaced Wizard 2 or 4 or whatever, and that buying these feats were taken from the core Wizard Class Feats.
Reading the Kindled Magic blurbs it looks a lot to me like you get bonus Lores, Skills, Feats and so on just by devoting your time to saying you are studying and passing rolls (presumably mixed with some RP) to advance your Branch Level as well as your Class Level.
Seems rather powerful, but I do quite like it.