separate icould and itunes account

Several years back I setup my kids iPads with a separate icloud and itunes accounts. The iTunes account was a shared account for app purchases and their i cloud was their personal account for cloud storage and to use facetime, imessage, etc. This was all setup before family sharing was introduced.

I recently got them a new iPhone 11 and trying to set it up the same way but cant for the life of me figure this out.

Can I still have a separate iCloud for them (use their existing one) and link all purchases (past and future) to my itunes account? If so, how do I do this?

If not, am I forced to use family sharing now?

Any advice would be appreciated.

thank you