Xcode - How to enlarge all the text and icons

Your screenshot is 2397x1345 px rather than the expected native 2560x1440 px.

Text and icons are noticeably blurry and a bit small, indicating that the image has been scaled down, presumably from 2560x1440 -> 2397x1345, resulting in a shrink to 93% in height and width.

You also have some odd tearing/multiple image artifacts in the screenshot (see the Bundle Identifier and Team controls). How did you take the screenshot? You can use cmd+shift+3 or the Grab app in Applications > Utilities to take screenshots.

Are you doing something odd on your end ?

1. Close any projects you have open in Xcode (Otherwise the Font window will be inaccessible while a project is open.)
2. Go to XCode > Preferences > Fonts & Color
3. From the 'Theme' box select the theme you want to modify (or select the theme you want to modify and click the "+" button at the bottom of the theme list to clone it first for backup, for there is no undo option)
4. In the source editor box there is a list of types of text that you may set the font for: Plain text Comments Documentation Comments . . .
5. Select any or all items from the source editor list and the name and size of the font for that particular text will show up in the 'Font' window below the 'Source Editor' window. (If you happen to skip highlighting one of these, you will be able to get to the Font Inspector and select new sizes, but will wonder why the changes you make are not being applied!)
6. In the 'Font' window, click the small, almost hidden, and surely poorly design 'T' icon to the right of the font name and size.
7. Voila! In only 14 keystrokes you are able to get the Font inspector window!
8. Your existing font will be preselected in the font inspector. Whatever changes you make now will be applied to the text types you selected in the 'Source Editor' window. e.g. All Fonts > Menlo > Regular > 14
9. Close the windows you opened on this hunt for the holy grail.

<Link Edited by Host>

Open System Preferences/Displays and adjust the display resolution to something less than 2560x1600? I can't remember if you can do so on a non-retina machine, you may need to hold down the option key when selecting the Displays panel in order to see more than the native resolution of your panel.

Most all non-retina display panels will support multiple (smaller) resolutions, although they will tend to look more fuzzy as a smaller number of pixels, is displayed on the same number of physical pixels.

Holding down the option key when selecting the *Resolution: [_] Scaled* checkbox does indeed show more resolutions.