Font sizes can be adjusted under Preferences / Display / Colors and Fonts.
Some icon sizes will adjust with the font sizes. For the toolbar icons which don't, they can be switched to larger versions in Customize mode. (For all but the File Display Toolbar, you can go to the Customize window, select the toolbar from the list, and flip the image size drop down to large. For the File Display Toolbar, you currently need to edit each button individually to set it to use a large icon.)
Alternatively, for the toolbar icons, install the Extra-Large Icon Set and move it to the top of the list, which will make all toolbars use the larger icons by default.