There are multiple ways for you to do this.
Option 1: On a Task
1 - Right-click on the task.
2 - Select Comment by Email.
3 - You will see a special email ID.
4 - Copy it and send emails to this ID to create comments in this specific task.
Option 2: From the Task Properties Window
1 - Open a task and its properties window.
2 - Click on the 3-dot icon in the top right corner of the window to open the option list.
3 - You will see a special email ID.
4 - Copy it and send emails to this ID to create comments in this specific task.
Limitations:
Outlook Web App: The comment will not be logged.
Microsoft Outlook (desktop): The comment will be logged, but the text may appear broken.