I like making PD communicate with other audio apps. I am not really that good at coding synths in PD.. and even if i were amazing, you can get sounds MUCH easier by using synths that someone else created. Unless you have some great synthesis idea that hasn’t already been done, why reinvent the wheel?
There IS an external that supposedly lets you load a vst into PD, but I’ve not had too much luck getting it to work in the past, so what I generally do when I want PD to play with a synth plugin is send midi from PD to a DAW that contains the plug.
The tool I use to do this is MIDI Yoke downloading and installing is a breeze, so no need to go into that.
After its installed, tell PD that midi out should go to MIDI Yoke channel 1 (or any of them really..) and then tell your DAW to get midi in from the same channel.
Check the PD documentation for any midi related object (they are all linked together in the help files) if you don’t know how to send or receive midi messages.