A regular refrigerator can be used in a garage.
However if the garage is not heated or cooled it can affect the operation of the refrigerator.
The temperatures in a garage can fluctuate from cold to hot and can cause issues with the refrigerator.
For example if the garage is always too hot such as in summertime the refrigerator will often run more often or even continuously to reach the cool enough temperature inside the refrigerator.
And in cold weather the refrigerator may not kick on much or at all in some cases if it's very cold.
Most refrigerators are designed to operate within a certain temperature range, which is often between 50 F to 110 F and garages can experience extreme temperatures during winter and summer.
The wide temperature swings in garages can affect the refrigerators ability to maintain consistent cooling.
And if the garage temperature drops below freezing then the refrigerator may not be able to properly cool the food inside and could cause it to freeze instead.
And if the garage temperature is consistently above 110 F then the compressor on the refrigerator may work excessively and could lead to the compressor burning out or even decreased efficiency.
You can use a regular refrigerator in a garage but it's best to use a garage ready refrigerator which is designed for the fluctuations and extreme temperatures in garages.