It's first choice on the instrument list, next to your previous used ones...
You can re-organize things to your liking.The same goes for the sampler and other stuff. Some times the legacy Logic instruments are there with all the synth functions showing and then - poof - there gone and just basic controls are available.
https://www.youtube.com/watch?v=84bG-WByv4Q
Legacy things
https://www.youtube.com/watch?v=coU70dSUXAA