All I can find is various predictions about the winners of games. Doesn't the margin of victory mean anything in this sport?
The margin victory does mean something in Rugby, especially with the 2019 World Cup rules where during the Pool stage,
A team scoring four tries in a match is awarded a bonus point, as is a team that loses by fewer than eight points...
We don't know you country, but if sports bet are legal in yours, in any website you should find bet details regarding points margin betting options. But in some countries, this options might be forbidden as betting is very country specific.