tex-parens

This package provides commands for working with lists, sexps and
defuns, much like those in lisp.el, but for tex buffers.  Here, the
role of parentheses is played by begin/end blocks, math delimiters
and mathematical parenthesis-like constructions (e.g.,
langle/rangle), together with their tex modifiers (e.g.,
left/right, bigl/bigr).  See README.org for more details.

You can activate it via `M-x tex-parens-mode'.  To activate
automatically, add the following to your init file:

(use-package tex-parens
  :hook
  (tex-mode . tex-parens-mode)
  (TeX-mode . tex-parens-mode))