Believe me, it’s impossible to create a website that will exactly meet the needs of every visitor. For example, a person with Dyslexia might need a very particular combination of text and background colours to comfortably read your page content.
You could contact someone who has Dyslexia and ask them about their preferred colours and then update you site to reflect those preferences. Does that sound like a good idea? Now you have a website that will work well for at least one person.
However, do all people with Dyslexia have the same access needs? The answer is no. Is your audience made up of only people with Dyslexia? I suspect the answer is also no.
A better approach is to design pages so that the presentation of content can be changed by the end user; in the case of the above example, ensure that each person can change the colours to suit their own needs (e.g., via browser preferences or a style sheet switcher).
This approach can be applied to all presentation aspects, whether it be, text size, layout, or the choice to leave graphics on or off. Design your site so that the presentation of your content can be changed by the end user. Do that and you don’t need to predict the exact needs of all of your visitors; which is an impossible task anyway.