Dungeon Crawl Stone Soup has a a very small font by default. On a 4k display, it
is barely readable. This is how I made it playable.
Make a file ~/.crawlrc with the following content:
# Adjust the sizes to your liking.
tile_font_crt_size = 32
tile_font_stat_size = 32
tile_font_msg_size = 32
tile_font_tip_size = 32
tile_font_lbl_size = 32
tile_sidebar_pixels = 64
To zoom in and out in viewport, press Ctrl+ and Ctrl- respectively.
All the possible options are documented in the Dungeon Crawl Stone Soup Options
Guide
file.