Say you and your wife pay 50% of new phone.

Then the rest is up to her :-)

that may help learn value of money...

19 hours ago, stubuzz said:

That would be an iPhone 11, released in 2019.

No, it wouldn’t. I was lucky to get one for around 4 to 5000 baht. Maybe others would pay up to 3x that. 
Either way, the answer should be no unless she has achieved something spectacular or you are very wealthy. 

Been there, done that! My daughter is now 18 yrs old. At 16.5 yrs she began selling on Shoppee (Live stream/

Clothes store) to fund her 1st purchase; an iPhone 11. Her sense of achievement has been great for her self-confidence. It spurred her on to then start working/saving again for her ist iPad. Both of these purchases within 18 months. My wife, younger son and I are proud of her dedication. Her schoolfriends are in awe! Yes, I could have purchased the products for her but would they have given so much "value" to our family if i had? I doubt it. As a grade 6 graduation gift/university entrance, we have bought her a Yamaha Grand Filano (72,000 baht) to get around her new surroundings. It's a 2-way street in our family.