You can zoom in and out on your Mac’s screen easily but you have to set it up first. Go to System Preferences, then Accessibility, then Zoom. Check the box to “Use scroll gesture with modifier keys to zoom.” You can choose the modifier key (I chose “Control”). Then, hold that key down and use your track pad or mouse to scroll. Easy.
You can also do it by keyboard shortcuts– set that up in the same dialog box. I find it easier to use (and remember) the Control-scroll method.