You would find it by yourself if you called it indent. Indeed, there are many interactive functions that start with indent. We easily find them with M-x indent TAB. But we can also find documentation with C-h ?, so if we try with C-h d RET indent RET to search in functions' documentation, or with M-x apropos RET foo RET we would also find them.
The following are built in and work with different languages (just tried with elisp, python and javascript):
M-x indent-region formats the selected region,
indent-sexp formats the current expression
There is no global option to configure the indentation, we need to dive in each mode's options. There is often options like (setq html-tab-width 4).
edit: some hints: (setq tab-width 8), (setq c-set-style "K&R"), (setq c-basic-offset 8) and with emacs' built in c-mode or GNU Indent you can switch styles: https://www.gnu.org/software/emacs/manual/html_mono/ccmode.html#Choosing-a-Style or https://www.gnu.org/software/indent/manual/indent.html#SEC4