Bonding can be used to change the size of a tooth. For a slight enlargement, there don’t have to be gaps between the teeth to fill with material – the teeth can be made larger by building up their front surface. Ideally, though, teeth are enlarged when there are gaps between them in the dental arch. Orthodontic treatment before bonding can distribute the spaces in the arch ideally, so that once they are filled with composite material the teeth end up a normal size.
This answer is for general information. Your own case needs an examination by an orthodontist.