Reference

Font Lookup systemfonts is primarily a package to facilitate the lookup of fonts based on typeface and style. These functions facilitate this
match_fonts() match_font()	Find a system font by name and style
font_fallback()	Get the fallback font for a given string
system_fonts()	List all fonts installed on your system
reset_font_cache()	Reset the system font cache
Shaping While text shaping is better handed off to the textshaping package, systemfonts does provide basic shaping functionality
shape_string()	Calculate glyph positions for strings
string_width()	Calculate the width of a string, ignoring new-lines
string_metrics_dev()	Get string metrics as measured by the current device
string_widths_dev()	Get string widths as measured by the current device
str_split_emoji()	Split a string into emoji and non-emoji glyph runs
Font file information The following functions allow you to extract various kind of information from font files
font_info()	Query font-specific information
glyph_info()	Query glyph-specific information from fonts
glyph_outline()	Get the outline of glyphs
glyph_raster()	Render glyphs to raster image
glyph_raster_grob()	Convert an extracted glyph raster to a grob
plot_glyph_stats()	Create a visual representation of what the various glyph stats mean
Local fonts While systemfonts was mainly created to access fonts installed on the system it also has rich support for using non-installed (local) font files from R. Further, it provides facilities for accessing system fonts that are otherwise inaccessible from R
add_fonts() scan_local_fonts() clear_local_fonts()	Add local font files to the search path
register_variant()	Register a font as a variant as an existing one
register_font() registry_fonts() clear_registry()	Register font collections as families
font_feature()	Define OpenType font feature settings
font_variation()	Define axis coordinates for variable fonts
Web fonts Many fonts are now available online through font repositories. systemfonts provide access to these, both for installing and using directly, but also for embedding inside SVGs
search_web_fonts()	Search font repositories for a font based on family name
require_font()	Ensure font availability in a script
get_from_google_fonts() get_from_font_squirrel()	Download and add web font
fonts_as_import()	Create import specifications for web content