There is definitely custom message tones in Oreo/Pie. Go to Messages, select the person who's message you want a tone for, click the 3 dots menu on the upper right corner and toggle "custom notifications" on, pick a message tone and done.
Sigh.... here we go again...
It doesn't work with GROUP messages. Before, you assigned a text tone to the individual though the contacts app, just like you can with the phone ringer tones. So I could assign Tone A for Person A and Tone B for Person B and Tone C for Person C. During a group/team message, when Person A would send a message, I would get Tone A. Person B would add something, and I would get Person B’s Tone.
NOW however, you assign the tone to the THREAD and not the PERSON. There is no individual tones for the PERSON.
The disadvantage is you must SAVE the ENTIRE message thread. If you delete the thread, there goes your customization for that thread/person. The present system/function does NO good for Group conversations which is about 70% of my conversations. I use group messages to communicate with my family. I use to to communicate with my friends. I use it to communicate with my co-workers.
For example. I get messages from my pharmacy from a computer about my prescriptions. I save them as a contact and assigned a quiet, simple beep. I don’t have to save my conversations with a computer. I can tell who it is and know that I can take my time and respond to them later. I've saved my alarm company as a contact and assigned a NASTY tone to them so that I know it's an emergency. My wife and two daughters all have separate tones. During a one-on-one conversation, I know who it is before I check my phone. But say my oldest daughter sends a group message. Before, I knew who it was right then. Now I get my default tone, unless I assign ANOTHER tone to that group and never every delete it.
Yes, I know about the three dots and assigning tones to the THREAD and not to the Person. I would like to have the personalized tones assigned back to the PERSON and Not the Thread. Just like it's been since Lollipop. Assigning the tone to the thread is not like what we had before and I have no idea why they eliminated that function.