You might enjoy the Scaler plugin a lot in fact. Actually I know you won’t be disappointed. It works as a midi plugin and can dramatically increase your knowledge of scales and chord changes and can actually read what you’ve laid down, tell you what would work next and give you mock versions you can try out and then drag and drop chords into a midi instrument. Here’s a link. Thank me later. https://www.pluginboutique.com/product/3-Studio-Tools/72-Utility/3933-Scaler
There is a plugin that already does this, one with all the additions people from the comments want added. It's called Scaler. https://www.pluginboutique.com/product/3-Studio-Tools/72-Utility/3933-Scaler
Scaler is helpful with Midi scales (not work with samples) but as another post pointed out, you can get the general scale from FL Studios Edison, then figure out the rest with scaler.
https://www.pluginboutique.com/product/3-Studio-Tools/72-Utility/3933-Scaler
Buy or download Scaler, pretty good vst when it comes to scales. https://www.pluginboutique.com//product/3-Studio-Tools/72-Utility/3933-Scaler?gclid=CjwKCAjwkenqBRBgEiwA-bZVtuvh7Fz2_gkhdfOxyA4w3jcl2xJnZEe4bRoQdGE_0EmLsMe59z2aYxoCBJMQAvD_BwE
Plugin Boutique Scaler displays the name of the chord you play on it, complete with extensions and everything, its pretty useful
I was having a similar issue recently. It was suggested I look up scales and chords in those scales. FLStudio has a way to highlight scales in the piano roll and the ability to insert chords. Look through the docs to see how to do this.
I found this nice plugin called Scaler that does most of the work for you. I’ve been using it and I like it a lot. https://www.pluginboutique.com/product/3-Studio-Tools/72-Utility/3933-Scaler
Once I know the scale and the chords I just experiment with different chord progressions until I get something I like. I hope this helps.
No, I don't sample much, I use VSTs (you can check my music at http://beatsbypao.com if interested). I mostly improvise and when it's not enough, I turn on the scale/chords function on my NI S49 or I load up Scaler - that is a tremendous tool for chord progressions overall, I recommend you check it out :)
I mix and match between these 2 plugins:
Between them I think they cover everything you asked for, plus a little more.