One of my first ones and my personal favorite is Konosuba, it's a great comedy Isekai. There may be a slightly weird scene or two once in a while, but for the most part it's kid-friendly
i would suggest "by the grace of the gods". its the most wholesome anime i know of, and as someone who doesnt get emotional too often i can tell you this one made me feel the warmest of fuzzies
Don't start with anything that is extremely long. keep it short. save the cringe shit for when she is actually really into anime. For action i would start with something like Black rock shooter. I also highly recommend Toradora. If you want something goofy then i highly recommend Lucky star and Azumanga daioh. An honorable mention is Metropolis 2001. I also highly recommend any studio Ghibli movies.
Not with the length, but the content. I think the game for Persona 5 is rated M, and coming from someone who played a little of it I wouldn't show it to a little sibling.
