Web browsers provide extra features to make web browsing more accessible.
Accessibility features are mostly controlled within the browser, however Chrome and Firefox have a number of extensions or add-ons that can greatly improve how web pages are accessed.
This Wikipedia page compares a limited number of accessibility features of a variety of different browsers.
The Chrome Browser section on this page explores accessibility features. There is a dedicated section on the Chrome Web Store for accessibility extensions. These tools will, for example, convert text to speech, enhance colors, and enlarge text and other parts of pages.
The Firefox accessibility features page describes Firefox's inbuilt accessibility features. Up until Firefox 57 (Firefox Quantum) there was as a good a selection of accessibility extensions for Firefox as there is for Chrome, Unfortunately the way that Firefox extensions work changed in Firefox Quantum and many extensions no longer work. Firefox 61 saw the inclusion of an 'Accessibility Inspector', which allows web developers to check the accessibility of their web pages.
The Access Firefox website is a good source of accessibility tools and resources for Firefox
Internet Explorer is no longer being developed by Microsoft, who recommend that you no longer use it as you default web browser.
The Internet Explorer ease of access page describes Internet Explorer's accessibility options. There are very few extensions for Internet Explorer.
The Internet Explorer ease of access page describes Microsoft Edge's accessibility options. There are some accessibility extensions for Microsoft Edge
Opera did once have a reputation as the most accessible browser, and the Opera site did have a dedicated page describing accessibility options, but no more. This page, which is a few years old now, describes how to turn on accessibility features on Opera . Like Chrome, the Opera extensions site has an accessibility section
This page describes Apple's accessiblity features, but does not mention Safari. This page, which is several years old, describes how to turn on accessibility features in Safari. There was a Safari extension gallery, but this was withdrawn. There is information about Safari extensions on an Apple support page, but nothing about accessbility extensions