Yes, that’s what the Find First Occurrence block is for. You can use it with the List of Values data source block to return the row number where the value is found. So if your data source has these values, for example:
Apple
Orange
Lemon
Lime
And the user inputs “Orange”, then the blocks would return 2 since “Orange” is in the second row. The blocks would return 0 if the value is not found in the data source.
You can see an example of this here: Thunkable and returns a corresponding value from my sheet - #6 by tatiang