I can find the best-fit polynomial function for the array, y = ax^2 + bx + c (where y = voltage output and x = incident temperature), and if I have arrays of data at flat fields captured at known ...

You can make a curved graph in Excel and Google Sheets using this tutorial. Learn how to convert sharp edges into smooth lines in a spreadsheet graph.

You can make a bar graph in Excel by first selecting the range you want to depict, and then using the dropdown menu to select the desired chart.