Error come with seo friendly url using .htaccess - apache

Question

Firstly I have coded my website in localhost than everything goes fine all URL work but when I upload it on the cloud (GCP) the URL is not working(It shows that the URL is not found)
the following code is of .htaccess file in localhost
RewriteEngine On
RewriteBase /blog_site/
RewriteCond %{REQUEST_FILENAME} !-d [NC]
RewriteCond %{REQUEST_FILENAME} !-f [NC]
RewriteRule ^single_post/(.*)$ single_post.php?post_title=$1
RewriteRule ^single_post/(.*)/ single_post.php?post_title=$1
RewriteRule ^category/(.*)$ category.php?category=$1
RewriteRule ^category/(.*)/ category.php?category=$1
RewriteRule ^author/(.*)$ author.php?author=$1
RewriteRule ^author/(.*)/ author.php?author=$1
RewriteRule ^author/(.*)/(.*)$ author.php?author=$1&user=$2
RewriteRule ^author/(.*)/(.*)/ author.php?author=$1&user=$2
RewriteRule ^search/(.*)$ search.php?search=$1
RewriteRule ^search/(.*)/ search.php?search=$1
RewriteRule ^([^\.]+)$ $1.php [NC,L]
Also use base tag
<base href="/blog_site/" target="_self">
On cloud server the code of .htaccess file is
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-d [NC]
RewriteCond %{REQUEST_FILENAME} !-f [NC]
RewriteRule ^single_post/(.*)$ single_post.php?post_title=$1
RewriteRule ^single_post/(.*)/ single_post.php?post_title=$1
RewriteRule ^category/(.*)$ category.php?category=$1
RewriteRule ^category/(.*)/ category.php?category=$1
RewriteRule ^author/(.*)$ author.php?author=$1
RewriteRule ^author/(.*)/ author.php?author=$1
RewriteRule ^author/(.*)/(.*)$ author.php?author=$1&user=$2
RewriteRule ^author/(.*)/(.*)/ author.php?author=$1&user=$2
RewriteRule ^search/(.*)$ search.php?search=$1
RewriteRule ^search/(.*)/ search.php?search=$1
RewriteRule ^([^\.]+)$ $1.php [NC,L]
and the base tag is
<base href="/" target="_self">
The VM instance link of GCP such that you can see how website behave
website link
If I manually type the url http://your_IP/contact.php working. But if I use http://your_IP/contact is not working

Answer 1

Based on your shown samples only, could you please try following Rules once. Please make sure you clear your browser cache before testing your URLs. There were multiple issues in your htaccess file, like conditions were not there, multiviews(which we came to know later in comments was ON) which made issues in your code.
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^single_post/(.*)/?$ single_post.php?post_title=$1 [NC,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^author/([^/]*)/(.*)/?$ author.php?author=$1&user=$2 [NC,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(category|author|search)/(.*)/?$ $1.php?$1=$2 [NC,L]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)/?$ $1.php [L]
EDIT by OP:
Please before you go forward please check .htaccess is enable it. If you don't know is enable or disable then type ---- in your .htaccess file, if it shows 500 internal error then its enable or it's disable. Then try to enable by searching on internet.