Replace text with new content from database

I’m building a website using WordPress that will modify its content based on the domain. There are a variety of reasons this is necessary. I have a table in my database and each row is specific to the domain.

Like plugins that allow you to [fill in the blank] and then it replaces that each time its found with the appropriate content.

The text that needs replacing is found throughout the website’s content. I can manually perform this by creating a page template for each page and custom widgets, but I am looking for an alternative solution.

Looking for ideas.

Thanks!
Luke