Write a plugin for the browser

The services of a web programmer are required. You need to write a plugin for the browser. You need a plugin (extension, script for tampermonkey) for chrome, which would replace the values on the site that gives javascript, according to given scenarios (up to 6 pieces), and, at the same time, without necessarily changing the functionality of the site (only values (for example, the FoxReplace extension comes (changes values, but the clickability of the inscription disappears)).

Mandatory requirements:
Extension for chrome/script for tampermonkey
Substitution of values according to given scenarios that can be set in the body of the script, or through the interface
Maintaining the full functionality of the site
Invisibility of the work to the user.