There are some accessibility standards for websites that can be quite stringent. The majority of websites do not get anywhere near 100% compliance to the most complex variants, and there are generally very large price tags around developing websites like this.
While I have not seen any yet, I am sure there are lots of people out there that can help you given a suitably large wedge of cash.
Look up WCAG 2.0 or WCAG 2.1
Guidelines from central government are tending to require that local government websites need to conform to these standards. It is likely to roll out further than that over time.
Some years back I worked as a volunteer for three months on a project for a visually impaired group. I tried really hard to meet all of their needs with customised CSS. It was the project from hell for me, especially as it was all free. We got there in the end, however it was a big learning point for me to keep away from specialist groups. Right at the end, the punch line was each member of this group had special (non standard web browsers) that did most of the functions anyway.
Accessibility standards can mean = ££££
Because you are likely to end up with a highly customised website with a lot of special code in it. This will ultimately become a support problem for the client, and a business opportunity to the supplier!
I work on the basis that the amount of customised code is at a minimum, so 99.9% of the website is standard. I also try to use some standard (popular and at least 4* rated) plugins to provide additional functions.
Can you crack the WCAG standard with plugins?
No, it needs a special approach to writing the website as well as having additional support in the site through plugins. However you can get closer to the standards, and provide help and guidance to users.
Some plugins worth a look at
I have recently been looking at this problem. One aspect of the problem is embedded codes in the website that special web browsers use to enable the accessibility functions. Like for example reading and navigating the website. Some templates may not include these, but some plugins may identify where they should go and add them in.
Here are two solutions, the first is for Divi users only as the first plugin fixes some shortcomings in the Divi template. As far as I can tell there is nothing visible from the normal users view after you enable the first plugin. The second however adds a disability icon in the top right of the website. Click on this and you can enable some of the functions.
DIVI only solution
Log into your website and go to Plugins and Add New. Do a search on the term: Accessibility. Look for the following two plugins: Divi Accessibility by CampusPress, and WP Accessibility Helper by Alex Volkov. Install both and activate both. I don’t think you need to anything special with the Divi Accessibility, that one appears to be largely dynamic. The codes added to the website will enable better support with Aria based Screen Readers using by people with visual and other impairments.
The second one has a few set up options. But here the text can be made larger, colours reversed, stronger contrast and a few other things. It is best to experiment. There seem to be a few options which are not available to you unless you subscribe to a premium version, however the free one seems to do quite a lot.
Non Divi websites
Just add and configure WP Accessibility Helper. Visit the set up screen and have a play with it. It is the same as the second step in the Divi solution above. As an experiment I have added this to this website. You will see a small icon in the top right of the screen which reveals a menu.
Got stuck? Contact me for help.