For S/4HANA Cloud product, you can write ABAP in BAdI implementations. Apart from that, I can't recall any other place where you can use ABAP.
It's worth noting that this ABAP is restricted ABAP, means you can't write every statement and only whitelisted keywords are allowed. Below link will give you more details about restricted ABAP:
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.