Got a question about music

Technically, it's two questions.

1: How do you make your sounds? Like, i know what a synth is but what i mean is, do you just have in your head what knobs to turn in order to get the sound you want?

2: Let's take Toby Fox for example. He has SOOO MANY VSTs or SoundFonts etc that i'm just wondering, how do you even find all of these