While you can find kid-friendly streams on Twitch such as this paleontologist, Twitch is NOT a kid-safe platform. In fact, Twitch prohibits use of the platform for under 13 year olds.
Any search or browse will bring up all sorts of cover-your-eye content. Twitch livestreams and replays are not - unless they specify it - geared towards PG content. It is VERY EASY to click to something that is not PG on Twitch.
In 2022, 41% of users were 24 and under. (And if you didn't know, the brain doesn't develop long term decision making capability until age 25 which is explains a lot.)
My point is this: if you have a stream you and your kid watch together, that's best. If you have a stream playing that they can't adjust or click around on, that should work.
Make sure you check it out first before you introduce it into your family.
That being said, if you find a great family friend teaching stream like that paleontologist, it's amazing content and a great experience to have live or on replay.