Here is the publicly available API for Company of Heroes 3. This will allow you to pull leaderboard information and game statistics. 


https://coh3-api.reliclink.com/


As an example you could use this to return all available leaderboards:
https://coh3-api.reliclink.com/community/leaderboard/getAvailableLeaderboards?title=coh3


Or use this to see the rankings for US Forces 1v1:

https://coh3-api.reliclink.com/community/leaderboard/getleaderboard2?title=coh3&leaderboard_id=2130255