Solution must be in R. Related questions are providing solution for other languages. (e.g., here freeze top row using spreadsheetgear)
An Excel counterpart of
library(tidyverse)
mtcars %>% write_csv('IneedExcelNotCSV.csv')
with some part of code that freezez the top row.
Solution for similar format to .xls(x) (e.g., OpenOffice) would work too. (.sxc?)