Single URL mod_rewrite keeps going back to the original URL - wordpress

Question

I am trying to do a very simple single URL rewrite.
This is it:
RewriteRule ^blog /?post_type=post [NC,L]
I would simply like example.com/?post_type=pos to redirect and display example.com/blog.
I have tried a number of different versions of the rewrite but all I have achieved thus far is that I don't get a 404 on example.com/blog but keeps going back to example.com/?post_type=post.
I have placed RewriteRule right at the top of the .htaccess file which didn't help.
These are the other rewrites I have in the same .htaccess file:
#Single URL
RewriteRule ^blog ?post_type=post [NC,L]
#http www rewrite
RewriteCond %{HTTP_HOST} ^instrumentrentalbarcelona.com [NC]
RewriteRule ^(.*)$ https://www.instrumentrentalbarcelona.com/$1 [L,R=301,NC]
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Answer 1

Thank you #DocRoot for helping me with this. The answer is detailed in the comment thread below by DocRoot and I. Just thought I would summarise this.
I wanted to show a page with all my blog posts.
This can be done if you use the WordPress post type "Post". example.com/?post_type=post
I wanted that page to show when you go to example.com/blog.
The following Rewrite works to show the desired URL: (thank you again #DocRoot)
RewriteCond %{QUERY_STRING} ^post_type=post$
RewriteRule ^$ /blog [QSD,R,L]
But /blog was giving a 404. So;
Create a page in WordPress called "blog"
Go to: Setting > Reading > Your homepage displays > Posts page: [Select page "blog"]
Save and done.

Answer 2

RewriteRule ^blog /?post_type=post [NC,L]
I would simply like example.com/?post_type=pos to redirect and display example.com/blog
The directive you posted does the exact opposite. It "rewrites" (not "redirects") from /blog<anything> to /?post_type=post
To redirect based on the query string you need an additional condition that checks against the QUERY_STRING server variable because the URL that is matched by the RewriteRule pattern is the URL-path only.
Try the following instead:
RewriteCond %{QUERY_STRING} ^post_type=post$
RewriteRule ^$ /blog [QSD,R,L]
This "redirects" from example.com/?post_type=post (exactly) to example.com/blog.
The QSD flag (Apache 2.4+) is required to remove the query string from the redirected request. If you are still on Apache 2.2 then you will need to append the substition with ? instead of using the QSD flag. eg. RewriteRule ^$ /blog? [R,L].
Not also, this is a temporary (302) redirect. If this should be permanent, then change the R flag to read R=301 - but only once you have confirmed this is working OK.