/usr/lib/R/site-library/utf8/INDEX is in r-cran-utf8 1.1.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 | as_utf8                 UTF-8 Character Encoding
output_utf8             Output Capabilities
utf8-package            The utf8 Package
utf8_encode             Encode Character Object as for UTF-8 Printing
utf8_format             UTF-8 Text Formatting
utf8_normalize          Text Normalization
utf8_print              Print UTF-8 Text
utf8_width              Measure the Character String Width
 |