如何使R基本图在边界框内更大？

Question

我正在R中创建两个图，一个在另一个上。问题是边界框内的图非常小，我基本上不知道如何“放大”。更改边距仅影响边界框的大小，而不影响内部的小图。任何帮助将不胜感激，因为我对此很陌生！

par(mfrow=c(2,1), mar=c(1,1,1,1))

plot(G_nwr,axes=FALSE,main="Non-weighted")
plot(boundary,add=TRUE)
points(G$utm_x,G$utm_y,pch=16,cex=0.2)
plot(roads_clip,add=TRUE,col="red",lwd=0.5)
plot(buildings_clip,add=TRUE,col="gray80")
plot(creeks_clip,add=TRUE,col="lightskyblue",lwd=2)
plot(railways_clip,add=TRUE,col="purple1",lwd=2)
plot(water_clip,add=TRUE,col="steelblue1")
legend("topright",inset=0.05, cex=0.8,
       c("Canadian Goose","Road","Building","Creek","Railway","Water Body"),pch=c(16,NA,15,NA,15,NA),lty=c(NA,1,NA,1,NA,1),col=c("black","red","gray80","lightskyblue","purple1","steelblue1"))