Well, if I changed the WordPress website address and URL to my domain (https://otapigems.com), then the site went into an infinitive loop of redirection and it was down (I changed back the settings already to get back it alive).
Installed and activated the WP Plugin ‘CloudFlare Flexible SSL’. I haven’t done any search and replace for http to https or whatsover, just activated the plugin
Changed both WordPress Address (URL) and Site Address (URL) to ‘https://otapigems.com’
That’s it. No more redirection loop, and the url stays as my custom domain and the connection is SSL.