As noted, there are different icons used in different applications. This makes it difficult to determine a universally understood standard. I remember Jakob Nielsen saying "Users spent most of their time on other websites." With this in mind, this is what i would do:
- Identify the target user group for the application you are designing for Y
- Understand which messaging / chat tool they are most used to, so
- Design icons very similar to the most popular messenger for the target group
By number of users, WhatsApp seems to be the most widely used messenger worldwide [data]. But if your target group is primarily based in China, chances are they use WeChat a lot. So you can use WeChat to inspire your icon designs. Those designs could be tested with real users to see if they understand the interactions, supported by the icons.
You can also consider text only as an alternative to icons, or icons along with a text label.