This question has been asked and answered a few times - most recently here - but are a few years old, involve a for-loop and grid, and are a bit hacky. I was wondering if there were any new ways to change the color of my strip text to match the title text, preferably within ggplot.
library(ggplot2)
library(ggtext)
facet_colors <- c("#43A047","#8A2BE2", "#007ACC")
iris |>
pivot_longer(-Species) |>
ggplot(aes(x = name,
y = value,
# group = Species,
fill = Species)) +
geom_boxplot() +
scale_fill_manual(values = facet_colors) +
labs(title ="Feature Comparison of <span style = 'color: #43A047;'>Setosa</span>,
<span style = 'color: #8A2BE2;'>Versicolor</span> and
<span style = 'color: #007ACC;'>Virginica</span>") +
facet_wrap(~Species) +
theme_minimal() +
theme(plot.title = element_markdown())

As you are already using
ggtext, basically the same approach applies to the strip text, e.g. using alabeller()function and settingstrip.text=element_markdown()too you could do: