The appendix package provides various ways of formatting the
titles of appendices. Also (sub)appendices environments are
provided that can be used, for example, for per chapter/section
appendices. The word 'Appendix' or similar can be prepended to
the appendix number for article class documents. The word
'Appendices' or similar can be added to the table of contents
before the appendices are listed. The word 'Appendices' or
similar can be typeset as a \part-like heading (page) in the
body. An appendices environment is provided which can be used
instead of the \appendix command.

Homepage:
https://ctan.org/pkg/appendix
