I see. I don't have formal musical training so apologies if I get some basic things wrong. Though personally I'm not too sold on the idea of substituting notes and using color tones unless it's explicitly asked for.
Its all good, thats the whole odea of the thread.
So, you're not substituting notes, per say. I'm sure you know, the root is the first note of a scale, it establishes the base of the chord tonality, though it doesn't need to be the bottom note. For example, a C major chord would be C-E-G, but a C6 (or first inversion) is E-C-G, and C6/4 (2nd inversion) is G-C-E, all are C major chords, and are interpreted as such.
Now most people think of chords I'm their base structure, 1-3-5. But, the fifth tone of the scale doesn't actually imply any major or minor tonality, it's why power chords on guitar are so versatile. Play a C and G only and you'll notice you can't tell if it's major or minor, you need that 3rd, or color tone, E. You may not be able to tell a chord completely from just C and G, but you can absolutely immediately tell the difference between C-E and C-Eb. In fact, id bet if I said nothing and played you C-E-C, you'd likely (rightly) assume I was playing a C major chord.
Additional tones add additional context. The 7th is the next most common color tone. C-E-Bb will immediately give C7 tonality, but just C-G-Bb doesn't quite distinguish between C7 and Cm7. This is also true of the 9, 11, and 13 (even numbers aren't often used in chord nomenclature to describe tones). Interestingly, you can omit the root and use 3-5-b7 (E-G-Bb in the key of C) and still call it a C7 chord.
So, for C-G-Bb we can assume the notes are either 1-5-b7, 4-1-b3, or 9-6-1, assuming the root is included. There are even more options if you decide everything involved is some sort of color tone.
As you can see, there's an absurd amount of theory you can apply to a set of 3 notes, and why the context around those notes is important. A piece in the key of C that uses a Bb as a color tone is incredibly unlikely to have, say, an F# chord in it, but could realistically have an Ab or even pivot through a Gb. I have probably 4 or 5 books just about how to navigate such things that I really need to crack into again.