It doesn’t take a 10 to make a review an outlier when a game gets such a low score (e.g. SoT). That Xbox score is 8 points higher than any other score and 19 points higher than the average (which will surely drop several more points, likely down to around 66).
8 out of 18 Reviewers gave the game a higher score than average yet you are going to complain about the Xbox bias sites? I personally played the game and I think the game is an 8/10 and I can see other sites loving the game while others will hate it. I don't see your point here. You want them to give the game a lower score on purpose? Isn't that what opinions are for? Maybe those Xbox sites love Sea of Thieves just like the other 6 sites rating it higher than average.