If you feel the display size of the apps are bigger in Moto G5 Plus, they can be made smaller by getting to Settings -> Display -> Display size. Tap the plus or minus buttons to get the display you wish, by making the adjustment. You also can see the preview in the above screen based on the changes you make..
To change the Font size, again go to Settings -> Display -> Font size. Use the small A or Big A buttons to change the font size which looks comfortable for you. Any time the display size or font size can be changed based on your comfort.
Reducing the size of icons looks great on the phone, also reducing the size of font gives sharper view of the text. But I don’t see a reason why there are no options of changing to different font.
Screen shot below: