Do you need a paid app for a first phone? Usually not. Here is what makes the free tools hold.
Honest answer from someone who has spent too long on this: for a first phone you probably don't need a paid app. Apple Screen Time and Google Family Link are free, built in, and cover almost everything; Bark and Qustodio sit on top of those same settings, they don't replace them. Reviews of the paid apps repeat the same failure: the kid deleted the app, or an update wiped the settings, and the parent found out weeks later.
What actually makes the free tools hold:
Set the parent passcode before the phone goes back to the kid.
iPhone: Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps > Don't Allow. Android: set everything from your phone first, then switch off Developer Options and USB debugging on theirs.
Test on the child's own phone. Open something you blocked. If it loads, nothing is enforced yet.
Put a monthly ten-minute recheck in your calendar. Updates and resets clear settings quietly.
Do YouTube, Snapchat, Instagram and Roblox one at a time inside each app; the phone-level settings don't reach into them.
One trap: Apple's screens differ by iOS version and by account country, so note both before following any guide, including this one.
The kit this comes from is the paid product on this page; the free 4-page preview shows one full step with its sources: https://whop.com/ai-digital-products-5c53/first-smartphone-kit-free-preview/