Recently I setup a computer for a friend with a visual disability referred to as low vision. So while he is not blind and can see it is still very difficult for him to see certain things. It is particularly difficult for him to differentiate the difference between colours that are similar to each other, for example a red object beside an orange or pink object or background would be too close for him to tell apart. Also, eye strain is an issue where things like small thin text and bright themes that use light grey on white cause unnecessary difficulties.
The computer I setup for him is running Solus (a Linux based operating system) and uses the Mate desktop. All the settings I mention below can also be found in other desktops like Budgie, Gnome, Xfce and KDE. Solus was chosen because it's a rolling release distribution. Rolling release means the operating system is installed once and is then kept up to date through regular system updates, no need to reinstall in order to upgrade to newer versions of software. So from that stand point its low maintenance. The reason Mate was chosen for the desktop was because it's lower on system resources then the other options (Budgie, Gnome, KDE) Solus had available.
To change the size of mouse pointer, go to the main menu (highlighted in the red box) and then select Control Center, located near the bottom in the left column in the menu. When the Control Center window opens head down to the "Look and Feel" heading and select Appearance. In the Appearance window there will be 4 tabs (Theme, Background, Fonts, Interface) click on the Background tab. Near the bottom of the Background tab you will see a button labelled Customize click on it. The Customize window will open and you should see 4 tabs (Controls, Window Boarder, Icons, Pointer), click on the Pointer tab. Near the bottom of the Pointer tab you should see a slider with the options small to large, slide it to increase the size of the pointer to the preferred size. While in the Pointer Tab you can also change the theme of the pointer, selecting the Mate option will give you a white mouse pointer.
Head back to the Appearance window and select the Theme tab. In the preview area for themes scroll down to the bottom, you should see a theme called High Contrast Inverse (this is a Dark high contrast theme) and select it. Now lets change the background to something less distracting, click on the Background tab. In the top left of the preview area for backgrounds select the greenish blue background. Now to change the colour, at the bottom of the preview area you should see a Colors drop down menu (Vertical Gradient is the default) click on it and select Solid Color. Now to the right of the Color drop down menu you should just see one colour box, click on it to select your desired colour. Now that the colours are taken care of lets adjust the font sizes for the various interface components.
Go back to the Appearance window and click on the Fonts tab. From within the Fonts tab you will see headings for Application font, Document font, Desktop font, Window title font, and Fixed width font along the left side of the window. When you click on the button beside the heading (just to the right) a new window will open titled Pick a Font. In the Pick a Font window you will be able to change the font used and in the bottom right corner of the window you will see where you can change the font size. Setting the font size will depend on how sever the persons visual disability is, my friend found that 15 was preferable for him. Keep in mind that none of these settings will effect the font size of the text used in the document of a word processor except for Fixed width font which as far as I can tell is only used by text editors like Gedit and Pluma that have a setting to enable it. So if you are wondering how to make the font used inside a word processor (like LibreOffice) larger without actually having to change the font size of the document you are working on and thus messing up your formatting here is a suggestion. With your mouse pointer over the document press ctrl and use the scroll button on your mouse to zoom in or out of the document. This will eliminate the need for having to change the font size of your document and as a little bonus it will also work in other programs like Firefox and LibreOffice Calc.
The Panel can be increased in size by right clicking on it and selecting Properties from the drop down menu. I find it easiest to right click on the panel just before the Separator (vertical line) beside the volume icon (looks like a speaker). From the Panel Properties window you can now increase its size by editing the Size section located under the Orientation section.
Finally here are the results of the changes that were made. Hopefully these tips are able to make it easier for you to see what you're looking at on screen.