ggwidth

install.packages("ggwidth") 
pak::pak("davidhodge931/ggwidth")

library(ggplot2)
library(dplyr)
library(ggwidth)
library(patchwork)

set_theme(
  theme_grey() +
    theme(panel.widths  = rep(unit(75, "mm"), 2)) +
    theme(panel.heights = rep(unit(50, "mm"), 2))
)

set_equiwidth(1)

p1 <- mpg |>
  ggplot(aes(x = drv)) +
  geom_bar(
    width = get_width(n = 3),
    colour = "black",
    fill = "grey",
  )

p2 <- diamonds |>
  ggplot(aes(x = color)) +
  geom_bar(
    width = get_width(n = 7),
    colour = "black",
    fill = "grey",
  )

p3 <- diamonds |>
  ggplot(aes(y = color)) +
  geom_bar(
    width = get_width(n = 7, orientation = "y"),
    colour = "black",
    fill = "grey",
  )

p4 <- mpg |>
  ggplot(aes(x = drv, group = factor(cyl))) +
  geom_bar(
    position = position_dodge(preserve = "single"),
    width = get_width(n = 3, n_dodge = 4),
    colour = "black",
    fill = "grey",
  ) 

p1 + p2 + p3 + p4

d <- tibble::tibble(
  continent = c("Europe", "Europe", "Europe", "Europe", "Europe",
                "South America", "South America"),
  country   = c("AT", "DE", "DK", "ES", "PK", "TW", "BR"),
  value     = c(10L, 15L, 20L, 25L, 17L, 13L, 5L)
)

max_n <- d |>
  count(continent) |>
  pull(n) |>
  max()

d |>
  mutate(country = forcats::fct_rev(country)) |>
  ggplot(aes(y = country, x = value)) +
  geom_col(
    width = get_width(n = max_n, orientation = "y"),
    colour = "black",
    fill = "grey",
  ) +
  facet_wrap(~continent, scales = "free_y") +
  scale_y_discrete(continuous.limits = c(1, max_n)) +
  coord_cartesian(reverse = "y", clip = "off")

mpg |>
  ggplot(aes(x = drv)) +
  geom_bar(
    width = get_width(n = 3, panel_widths = unit(160, "mm")),
    colour = "black",
    fill = "grey",
  ) +
  theme(panel.widths = unit(160, "mm"))