Don't think because Chelsea managed to win the fifa club world cup this season, they would also easily win the coming premier league title, from my personal knowledge and what I've seen so far, the premier league competition or tournament is usually one of the toughest football game in the history of football games, the tight competitions always ensures that only the best end up winning at the end of the day, not just the best but also the luckiest as well.
So, Chelsea definitely have a chance and what it takes to win the premier league next season, but i won't be betting on this honestly, for even with their signings, they may not perform in the premier league as good as they did in the fifa club world cup tournament.
I know the Premier League is one of the toughest tournaments in the history of football, but it is now easy to predict the strong contender for winning the Premier League title because only two clubs, Manchester City and Liverpool, have been winning the Premier League title consecutively for the past eight years, but that doesn't change the fact that the Premier League is still not the toughest league, it's still the best. The reason I listed Chelsea as as one of the strong contender to win the Premier League trophy is that they are playing well right now, they won conference and club world cup titles, and they are still improving their squads for the upcoming season. However, there is one thing about Chelsea that I don't like, which is that I can't bet on them to win the Premier League because they play well against strong teams but easily concede when they play against weak ones.
There's a significant difference in quality between the FIFA Club World Cup and the Premier League. Chelsea did well by winning the FIFA Club World Cup, but it's difficult to replicate that kind of performance in the league because the league is a longer process and teams' performances can fluctuate. Competition is fierce in the Premier League, and success isn't easy.
Finishing ahead of Manchester City and Liverpool isn't easy because, as you mentioned, they usually win the championship. Chelsea's performance suggests they're a team capable of challenging City and Liverpool this season, but things will become clearer once the league starts.