Change font and text size in ggpairs plot

Question

this is my code for a ggpairs plot:

library(ggplot2)
library(tidyr)
library(GGally)
           ggpairs(data = Food,
          mapping = aes(color = "darkorange"),
          columns = 2:4,
          upper = "blank",
          diag = "blank",
          axisLabels = "none",
  
          ) +
      theme_bw() + scale_color_manual(values = "darkorange") +
      #theme(plot.caption = element_text(face =  "TT Times New Roman")) +
      #theme(text = element_text(family = "A")) +
      #theme(axis.text = element_text(size = 8)) +
      labs(caption = "Källa: Coop", title = "Sambandet mellan olika produkter") + 
      theme(plot.title = element_text(hjust = 0.5)) 

I need to change the font of the text in my plot to Times New Roman as well as increase the size of my text inside each column. The code after "#" doesn't work and I wonder whether someone could help me get this right.