How can I select the latest message that's linked to my conversation table?

select 
  conversations."createdAt",
  conversations.id,
  array_agg(json_build_object('id', "conversationMembers"."userId", 'avatar', "userData".avatar, 'username', "userData".username)) as "membersData"
from 
  conversations
join 
  "conversationMembers" on "conversationMembers"."conversationId" = conversations.id
join 
  "userData" on "conversationMembers"."userId" = "userData".id
group by 
  conversations.id
order by 
  conversations."createdAt" desc