I have data in cells drop down. How can I make it recognize the same data or first letter of the data drop and auto fill? Does this make sense?
This feature isn't supported in the dropdown lists.
But there are some third-party tools for this, such as this one.
The easiest workaround I suggest is to make the data validation source list somewhere in the same worksheet.
Then create a chain between the data validation dropdown list and the data source.
The chain trick is explained in this video.
Hope that helps