Precautions to take to update WordPress safely
1. Check the compatibility of updates
The WP Safe Updates plugin or similar ones help you to test your plugin updates in a safe environment. Without focusing on complicated technicalities, when you install the plugin, you'll see an option for test update which is added to each plugin. That's where you can do this check before updating. With these systems, you can detect potential conflicts that would be caused by updating a particular plugin before it happens.
In fact, any changes that are generated with the update can be seen and reviewed before being applied in the real environment.
Obviously, if the update test caused a conflict, being in the test environment, it would not affect your website and you can desist from updating the plugin.
2. Work with a child theme
At this point, to update and maintain the WordPress page without losing anything, you should already be working with a child theme. This is, rather, a reminder.
Working with a child theme helps you prevent job loss, when you are updating the parent theme, which you are using on your WordPress website.
In the child theme in WordPress, the customization that you have made to the code of the parent theme is saved, for example, changes in the web design (CSS) and programming customizations (PHP).
If you do not have a child theme, it is likely that, when updating the theme of your website, you will lose all the changes made to the design and programming.