Hi...
This is what mentioned in Qatar airways website...
No exceptions for Minors traveling from countries on the Red List.

a) Minors between (0-11) years old are not allowed to enter.

b) Minors between (12-17) years old traveling from countries on Red, Yellow & Green list countries.

b1) who are fully vaccinated are allowed to enter without quarantine.

b2) if not vaccinated will not be allowed entry

https://www.qatarairways.com/en/travel-alerts/requirements.html