I'm trying to export some data with formats into Excel. It works ok, but the columns size get not properly adjusted. I don't want to use some complicated solution based on this example.
In my tests, I tried a code like that:
data = {{"Column 1", "Column 2"}, {1, 4}, {2, 5}, {3, 6}};
data[[1]] = Style[#, Bold, Red, FontSize -> 15] & /@ data[[1]]
Export["data.xlsx", data, "FormattedData"]
I get this result:

And I need something like this:

Some clue?
