Вы должны изменить его с помощью аргумента show.legend
.
library(tidyverse)
library(sf)
data(meuse, package = "sp")
meuse_sf = st_as_sf(meuse,
coords = c("x", "y"),
crs = 28992,
agr = "constant")
ggplot() +
geom_sf(data = meuse_sf, aes(colour = landuse), show.legend = "point")
![enter image description here](https://i.stack.imgur.com/RY2xR.png)