One question on this subject, answered from our own work, with the numbers.
Dubit found that age 12 is the year social features unlock. Our February 2026 study of the five big social platforms measured each single year of age from 10 to 12. It asked about 204 to 210 young people at each age. On several of those platforms the jump from 11 to 12 is sharper than the jump from 10 to 11. Snapchat direct messages rise from 18.6% of 11 year olds to 25.7% of 12 year olds.