If you mean a photo which is already uploaded and is the 'profile image' - you can't change the software. However, the larger version will appear on the right-hand side of the profile as well.
If you mean a photo which is already uploaded and is standing as someone else's 'profile image', but looks tiny, it is to do with the privacy levels set by that person.
If you mean a photo which is already uploaded and you are using the code in the text, such as
{{Image|file=RNH_Images-89.jpg
|align=r
|size=75
|label=Ball
|wrap=y
}}
then you fiddle about with the 'size=75' as above until you get it the way you want it.