You can find all the results on google. You can start by googling what the premier league of each country is called. Then start searching for stats for those leagues to see if someone did the work for you.
If no one cared to do the work then try to see what stats the regional broadcasters are keeping on their websites.
ESPN scrum should be a good start. I'm not too sure how good the rugby site is but their cricket equivalent is the standard app Journalists use worldwide for data.
if none is available you will need to for a specific country you will simply need to visit official websites of that league and browse through historical records of results and compile the data.
If you can do this the rugby community will thank you, but don't underestimate the task.
Also, the fact that you asked and did not straight up google it is slightly worrying when compared to the good traits of a statistician. But that could be subjective!
ESPN Scrum has great stats, for international games, on a match-by-match basis,
Premiership Rugby has the same for Prem games
In terms of collated results (i.e. "In 2019 X player made Y tackles) I've not come across anything,
Premiership Rugby site, for example, just shows you the "headlines" (i.e. points scored, tries scored, games played)