You can use the user-select property to disable the text selection of your blog post. For this, you need to add some CSS code to WordPress. Log into your WordPress as an admin; go to Appearance -> Customize. There should be a link for "Additional CSS". Click on that and paste the following CSS into the textbox and click on the publish button.
* { -ms-user-select: none; /* Microsoft Edge */ -webkit-user-select: none; /* Safari */ -webkit-touch-callout: none; /* iOS Safari */ -moz-user-select: none; /* Old versions of Firefox */ user-select: none; /* supported by Chrome, Opera and Firefox */}
Now text on your blog will be protected from a normal user. Tech users can still view the source code and copy the text.