Hi @Shengyou_Zeng and @Bryan_TeamKickstart 
I was thinking of adding a custom field to set the priority, but custom fields can only be added to Projects, not to My Tasks, so that would require to add a custom field on each of your projects…
Another solution would be to create custom sections in your My Tasks, for example under “Today” you could create 3 new sections (P0, P1, P2) to organize your tasks for Today base on priorities! The example given in this post is a good illustration of how you can leverage sections to organize your My Tasks! 