See my code
library(flextable)
library(officer)
library(magrittr)
my_doc <- read_docx()
tb = head(iris, 4)
tb <- flextable(tb)
tb <- width(tb, width = 1.1)
my_doc <- my_doc %>%
body_add_flextable(tb, align = 'left')
print(my_doc, target = "file.docx")
Word output
PDF Output > same document saved as pdf