I dated a guy whose family had some canna in their yard. It had no flowers but it had some seed pods, so I harvested some seeds, which look like all other canna seeds. The foliage was a pretty dark red. Do you know what species of canna that is?
It is hard to say without the flowers. Also, there are cultivars with red leaves, such as 'Australia' and 'Intrigue', but they won't necessarily come true from seed. Many cannas grown in gardens are hybrids, rather than straight species, and their offspring often reflect their mixed ancestry.