Consoles of different brands that fight a competition are always published at the same time. 7 years ago, the playstation 4 and the xbox one came out not only in the same year, but also in the same month, and so it will be again this year with the new editions, but why? Only one brand would have to publish its console a year earlier, for example, and it is likely that it will win the competition because nobody wants to wait that long for the other brand.
It is always the case that most of the money can be made with the Christmas sales. IPhones will also be released in late September so people can save money until Christmas.
And why the same year?
Because you can't afford to just let your competitors go. If the ps5 were released this year and the new Xbox only in spring, then many would get the Playstation and not the Xbox. If both come out at the same time, everyone will be happy and you wouldn't have to switch.