Is this what you are trying to do?
library(tidyverse)
sample_df <- data.frame(stringsAsFactors = FALSE,
check.names = FALSE,
`Locale name` = c("Greedgware","Headbon Beach","Nia",
"La Droclearlau","Mount Gatier",
"Restrol","Port Belltowncalne",
"St. Bamprksworth","Ioaks",
"Kitchaca"),
`% residents who support principal leader` = c(93,48,94,
38,91,49,31,6,78,5),
`% residents who oppose principal leader` = c(7,52,6,
62,9,51,69,94,22,95)
)
sample_df %>%
rename(pSupport = `% residents who support principal leader`,
pOppose = `% residents who oppose principal leader`) %>%
pivot_longer( -`Locale name`, names_to = "position", values_to = "percentage") %>%
ggplot(aes(x = percentage, y = `Locale name`, fill = position)) +
geom_col() +
scale_x_continuous(labels = scales::percent_format(scale = 1))

Created on 2021-12-15 by the reprex package (v2.0.1)
I'm sorry but this phrase is not clear to me, I don't understand what you are referring to, I think you are misunderstanding what the arguments for the pivot_longer() function should be, maybe this article would clarify things for you
Also, please test your reprex before posting, the one you have posted here had syntax errors that made it a little harder to take a look into your issue.