Elio Rivero

This plugin will enable the TinyMCE rich text editor for the title field 
when writing a page or post. Requires jQuery to work, but rather than 
including it with , the plugin will enqueue the jQuery library 
included with WordPress using wp_enqueue_script on the admin area.
There are a couple of style to remove the margin between the title 
label and the TinyMCE editor area, and the padding around the title 
box and the border.
Beware, for this plugin will paragraphise all your titles, so what 
once was a h3 headline in your styles now might be h3 p.
This software is provided without warranty of any kind.

ILC Rich Title

Enables TinyMCE for the title when writing a post or page.

Scott Reilly

By default, WordPress only allows 30 custom field names/keys to be listed in the dropdown selection ‘Name’ field when writing a post or page. If you, or the plugins you use, make use of a lot of custom field key names, you may surpass the default limit resulting in some custom field keys not being listed. This may force post authors to manually type in custom field key names if they aren’t listed, which increases the chances for naming errors (typos, or not using the precise key name that is needed). This may also cause some authors concern wondering where previously used custom field keys have gone since they aren’t listed.
This plugin increases the limit to 200 custom field key names.
There is no settings page to customize the default value. If you’d like to list some number of custom field key names other than 200 (say, for example, 100), you can do so in either of two ways:
<ol>
<li>By editing your wp-config.php file and at the end adding a line such as: 
define( ‘CUSTOM_FIELD_NAMES_LIMIT’, 100 ); 
-or-</li>
<li>Somewhere — ideally in a mu-plugin or site-specific plugin, or less ideally your active theme’s functions.php file — hook the ‘c2c_list_more_custom_field_names’ filter and return the number you’d like to use: 
add_filter( ‘c2c_list_more_custom_field_names’, function ( $limist ) { return 100; } );</li>
</ol>
Note: This plugin has no effect for users who make use of the block editor (aka Gutenberg) introduced in WordPress v5.0 because that editor does not directly expose custom fields in the interface.
Links: <a href="https://coffee2code.com/wp-plugins/list-more-custom-field-names/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/list-more-custom-field-names/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/list-more-custom-field-names/" rel="nofollow ugc">GitHub</a> | <a href="https://coffee2code.com" rel="nofollow ugc">Author Homepage</a>

List More Custom Field Names

Allows for more existing custom field names to be listed in the dropdown selection field when writing a post.

ILC Rich Title vs List More Custom Field Names