Here is the full list of all 22 The Timeless Child - there are Prologue achievements.
Complete the prologue playing as Chris Hunt
Complete the prologue playing as Emily Wells
Ring the Time Bell for the first time
Open the map for the first time
Play with a friend for the first time
Find and read all sheets
Listen to all George Wells tapes
Try to access the basement playing as Chris Hunt
Solve Books Puzzle without ever making a mistake
Solve School Puzzle without ever making a mistake
Help solving Greenhouse Puzzle without ever making a mistake
Solve Paintings Puzzle without ever making a mistake