Here are some important takeaways to protect your site from unwanted spam posts:
Use long, complicated, and secure passwords to protect your site. For example, this free Password Generator tool comes in handy whenever you need to change a password or create a new one.
Add additional security measures to your wp-admin panel like 2FA and limiting login attempts
Stay on top of software updates. As a website owner, you should make it your responsibility to regularly check your WordPress site for any out of date software. Plugins, themes, and WordPress itself constantly come out with new versions that patch security vulnerabilities and add new features.
Make sure to delete any unused WordPress administrators. (The fewer access points, the better.)
If possible, isolate your website to avoid cross contamination.
Place your website behind a firewall service.