Cambiar el upload_max_size de php para WordPress

How to Check Your Maximum File Upload Size Limit in WordPress?

WordPress will automatically show the maximum file upload size limit
when you are uploading images or media. To check it you can simply go to
Media » Add New page and you will see the maximum file uplaod size limit for your WordPress site.

1: Theme Functions File

There are cases where we have seen that just by adding the following code in theme’s functions.php file, you can increase the upload size:

2. Create or Edit an existing PHP.INI file

For this method you will need to access your WordPress site’s root folder by using FTP or File Manager app in your hosting account’s cPanel dashboard.
In most cases if you are on a shared host, then you will not see a
php.ini file in your directory. If you do not see one, then create a
file called php.ini and upload it in the root folder. In that file add
the following code:

This method is reported to work for many users. Remember if 64 doesn’t work, then try 10MB (sometimes that work).

3. htaccess Method

Some people have tried using the .htaccess
method where by modifying the .htaccess file in the root directory, you
can increase the maximum upload size in WordPress. Edit the .htaccess
file in your WordPress site’s root folder and add the following code:

Again, it is important that we emphasize that if you are on a shared
hosting package, then these techniques may not work. In that case, you
would have to contact your web hosting provider to increase the limit for you.

We hope this article helped you increase the maximum file upload size
in WordPress. If you are still having issues, then follow the steps in
our WordPress troubleshooting guide to fix it.

Fuente: https://www.wpbeginner.com/wp-tutorials/how-to-increase-the-maximum-file-upload-size-in-wordpress/

Ok. Si hiciste todo esto y no funciona.

Falta reiniciar los servicios.
service httpd restart

Si no funciona, también reiniciar php-fpm

service php-fpm stop
service php-fpm start