This question really depends on when you want to add the fruit. You can most definitely top your finished ice cream with any garnishes you like including strawberries and other fruit.  However, if you want to turn your vanilla ice cream into a strawberry or fruit ice cream, you can't just throw fruit in there and freeze it all together. You could do this, but because fruit has a lot of water, you’ll end up with chunks of icy fruit disrupting your smooth and creamy ice cream experience. So, in order to add fruit to the freezing process, you will need to macerate the fruit and then add it.