@kpatel - Directly adding the tooltip on the textbox is currently not a feature of quicksight but we can do it in a different way.
Could you please have a look at this post for some ideas -
- How to add a tooltip which displays simple text on visual while hovering
- Arena Example - How to add a tooltip which displays simple text on visual while hovering - #2 by ErikG
Let me know if that helps.
Thank you,
Shravya