for just a by-the-numbers tutorial, here's a video of how you'd sidechain using pro-c. i dont personally use pro-c, i use a peak controller (which is arguably more convoluted), but that tutorial should get you where you wanna be.

also, some things that help a lot with getting more control out of sidechaining:
dont be afraid to sidechain only specific frequencies out. (i.e. you can drop out a whole bassline, or just the lowend)
use multiple SCs for individual instruments (smaller ones on the lead/pads and larger ones on the bass, etc) to let things breath more
use shorter samples, like a trap snare or white noise, to trigger the SC so you can adjust the release yourself.

Watched the vid and it helped a bit. But I still I know of 2 different ways to sidechain in fl (pro-c and using the limiter compresssion), but I still don't know how to sidechain into specific frequencies by doing that. IE, on this song I'm currently working on when the kick/sub and this airy whistle I made play together it causes a clipping noise on said frequency. It's on the punchier fqs of the kick and I'm wondering how I can sidechain just those frequencies specifically and haven't found anything guidewise. :/

Thank you for the help so far though!

Nicky Romeros Kickstart Vst is very helpful with sidechaining

That's automated sidechaining. I need reactive sidechaining. 2 different things.

Just for the sake of education, I wanna point out that "sidechaining" isn't just what most of us think of as sidechaining - but ducking. We're using a sidechain trigger - where an effect like an EQ, a gate, or a compressor is activated based on the input of the signal sent to it - to cause the audio signal to "duck" out of the way on regular intervals or when receiving an external sidechain impulse.

Something like VolumeShaper/LFOTool/Kickstart can be used to reactively duck by creating an empty MIDI signal that is fed into whatever track you have the plugin on - with the first two you even get custom shaping of how the audio is cut!