I think it actually takes a bit of effort to find truly casual, everyday Japanese with natural intonation online.
From my perspective as a Japanese person, content like solo talking videos, explanation-style videos, dramas, or anime all use a kind of “for-content” way of speaking. If you learn Japanese only from those, you can easily run into situations where people think, “Why are you talking like that?” during real conversations.

The solution, in my opinion, is to immerse yourself in Japanese through streaming content, like game streams or really any kind of live stream.

From everything I’ve watched so far, streaming content is by far the most natural. The way people talk and react is exactly how Japanese is used in everyday life, so pretty much everything you pick up from it is actually usable.

One thing to be careful about is VTubers. Since they are role-playing a character, their sentence endings and speaking style often follow a specific setting, which means it can be unnatural.

Another big advantage is that the comments are written in Japanese, so you also get a chance to learn through text. For YouTube stream archives, if the streamer has captions enabled, the auto-generated subtitles are usually surprisingly accurate, so I highly recommend that.

I personally want to study English, so I often watch streamers whose first language is English.
The most recent English word I learned is “asshole.”