There are many hitting drills available on YouTube. Some are better than others. Many drills on YouTube are NOT EFFECTIVE at teaching a modern fastpitch swing. The following YouTube channels have been vetted to ensure they will teach and promote mechanics consistent with an effective swing:
Hitting is both a physical and mental exercise. When players go into the batter's box, they should be mentally prepared. Watch this video by Amanda Scarborough that talks about the mental approach to hitting: https://www.youtube.com/watch?v=ON-hx6SuiEU
Drills for the Hitting Progression
Other Good Hitting Drills
Lightning: You can do this with a front toss or pitching machine: have the team go through in rounds, each hitter gets one swing; each round it gets progressively more difficult, go until there's only one person left. You can make it more difficult with the rounds in a couple of ways. One way is to require contact on the first round, fair ball on the second, line drive on the third, line drive up the middle on the fourth. You can also make it more difficult by moving the plate closer to the pitcher each round to work on timing, or you can increase the speed of the pitch/machine each round.
You can also do this drill with bunting: first round contact, second round fair, third round directional one side (left/right/center), fourth round directional other side, etc.
Bucket game: this is a classic game within BFA, try adding on to it by putting a player on the bucket instead of an inanimate object.
Cat and mouse (especially for 8U)