Wheel Tire Height Change: 27Plus to 29
The difference between 622mm rims on 29” wheels and 584mm on 27.5” wheels is only 19mm - about 3/4 if an inch. If you run a narrower tire the rim plus tire diameter different is even less. 

In general bike frames do not have clearance for larger wheels so this may not even be possible. 

Note that larger wheels will also change your steering geometry.