latexindent is a perl script that can help you format LaTeX files. It is shipped with texlive (at least 2020 version). To use it you have to install some other perl packages.
Step 1. Install perl
sudo apt install perl
Step 2. Install the perl package management tool cpanm.
sudo cpan -i App::cpanminus
Step 3. Install the needed perl packages
sudo cpanm YAML::Tiny sudo cpanm File::HomeDir sudo cpanm Unicode::GCString sudo cpanm Log::Log4perl sudo cpanm Log::Dispatch::File
Step 4. If everything worked, you should be able to see the help information of latexindent by