Redirect with htaccess if required file exists?

Question

htaccess

Good afternoon
I now have such an interesting line: RewriteRule ^(.*)$ index.php?htaccess&l=$1 [L,QSA]But you can immediately see that everything is through one file and this is a bad habit ..
I would like to start breaking everything down, but I'm not ready to change everything right away.
Is it possible to somehow "combine" that line with RewriteRule ^(([^/]+/)*[^.]+)$ $1.php [L,QSA]if the desired file really exists and is located in this folder or in the folder, say, code?

Answer 1

RewriteEngine on

RewriteCond %{REQUEST_URI} ^.*([^/.]+)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/.]+)$ sys/$1.php [QSA,L]

RewriteCond %{REQUEST_URI} !^/index\.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* index.php [L]