Coinmarketcap got a section for this - https://coinmarketcap.com/events/
But for me, it's not really more information as it is not their main use, but you can still use it and use multiple platforms such as Coinmarketcal (much advisable).
There are a lot of new platforms now, I can add Coinpredictor (https://coinpredictor.io/calendar).

My advice is always to verify after using these kinds of platforms, like checking different social media or announcement platforms of every project you found, like checking their Twitter account or telegram or discord to verify if this platform listing is legit.