This first step is only relevant if your WordPress site is on a server that you control, and to which you have SSH access. The default settings for Linux, Apache, MySQL, and PHP generally work well for most WordPress sites. One exception however is the “Maximum File Upload Size” in the PHP settings which defaults to 8mb. Most custom theme packages and custom plugins are larger than 8mb and so this setting is a common stumbling block on new WordPress sites; so much so that we should preemptively set it to a higher value.
The PHP configuration file is located at /etc/php.ini. There are two sets of parameters that you should check and potentially adjust. The first is on or around row 657. Modify post_max_size to 128M.
The second is on or around row 800. Ensure that file_uploads = On, then modify upload_max_filesize to 128M and max_file_uploads to at least 20.