The openxlsx2 package uses global options to simplify formatting:
options("openxlsx2.borderColor" = "black")
options("openxlsx2.borderStyle" = "thin")
options("openxlsx2.dateFormat" = "mm/dd/yyyy")
options("openxlsx2.datetimeFormat" = "yyyy-mm-dd hh:mm:ss")
options("openxlsx2.numFmt" = NULL)
options("openxlsx2.paperSize" = 9)
## A4
options("openxlsx2.orientation" = "portrait")
## page orientation
options("openxlsx2.sheet.default_name" = "Sheet")
options("openxlsx2.rightToLeft" = NULL)