This R-package allows for easy insertion of datalegreya font by figs into R Markdown documents.
You can find the vignette here. Note that the font take a moment to fully load.
You can install this package from github as:
# install.packages("devtools")
# devtools::install_github('emitanaka/datalegreyar')
install.packages("datalegreyar", repos = c('https://emitanaka.r-universe.dev', 'https://cloud.r-project.org'))