I can help you.

A teen who loves art!!! And being able to get to them before "adulthood" and conforming and being bland and dull and colorless has set in. I love threads like this!

This is an exciting time for her. You are a great mom for encouraging her. There are many, many FREE projects online with great teachers.
I don't think there are in-person classes at Michael's now due to COVID. However DO use a 40% - 50% off coupon every time you shop for crafts & art supplies. You can just show the online coupon on your phone and they scan it. Have your DD make a separate purchase, using the coupon again for more savings.
https://www.michaels.com/coupons
Michaels, AC Moore & JoAnn's Fabric each take competitor coupons from each other if the other store happens to have better coupons that week instead. JoAnn's does have an art & craft section.
https://www.joann.com/coupon/
https://givingassistant.org/coupon-codes/acmoore.com
For online painting tutorials, I highly recommend these online painting teachers below. They also have corresponding Facebook groups for their students to share tips, paintings and enthusiastically support each other, if you feel comfortable with her joining in and chatting with fellow beginners, amateurs and artists, who also enjoy painting. MANY started out doing only the tutorials of these teachers and did so well that within a couple years or so were selling their paintings at little community art fairs and such. Their FB groups are well moderated, so she should be safe in the groups. Before the pandemic, many people used to do painting parties to these tutorials, with friends & family members all painting together while watching a specific project being cast on the TV:
Angela Anderson: (she has easy beginner paintings)
https://www.youtube.com/channel/UC8XDBvQQ6bh_myqOgThGK7Q
Corresponding Thankful Art Facebook community group
The Art Sherpa: (also has beginner projects.)
https://www.youtube.com/user/HoneyBmama
Corresponding Art Sherpa Facebook community group
Painting with Jane:
https://www.youtube.com/channel/UCW4Afe-CtYM5kp6FJEUPTFA
For great, yet inexpensive paintbrushes, my favorites are the Loew Cornell, synthetic, amber brown bristle, flat or round paintbrushes. (Assorted sizes, but a #6, #8 or #10 flat will work for most everything.) You can get them at Michaels. They work well without going limp when wet. They have a nice snap or spring to the bristles in coming back to a nice point, after being pressed down on paper or canvas, flattening out the bristles and then letting up on the pressure. That makes them so great for most techniques, especially scrubbing in colors or softly blending layers of adjoining colors together.
Flora Bowley does "intuitive painting," in which she does a combo of free-form doodling with cheapo foam brushes from Walmarts house paint dept, her FINGERS, (yes, tween/adult finger painting!) and stencils & sponges, feathers, etc. She basically gives permission to play and use a LOT of colors.
I LOVE watching this video of Flora's:
And there's these painting videos below for more free-form, no paintbrush techniques. They are really mesmerizing.

All they need is a mix of acrylic paint and Elmer's glue. The technique is called: String pull acrylic pour. Also chain pull, if you have an old light bulb fixture that uses a ball chain to turn on & off.
String Pull/Chain Pull painting technique