Here is the full list of all 45 Hogwarts Legacy achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Complete all collections
Find all Demiguise statues
Find the Map Chamber as a Ravenclaw
Find the Map Chamber as a Gryffindor
Find the Map Chamber as a Hufflepuff
Spend all Talent Points
Reach Level 40
Complete all side quests
Reach the highest point in the castle, the Headmaster's upper study
Complete all Merlin Trials
Discover all cairn dungeons
Breed every type of beast
Upgrade a piece of gear 3 times
Unlock all Floo Flames
Win the House Cup
Defeat enemies in all battle arenas
Use Ancient Magic on every enemy in the game
Rescue the phoenix
Complete Poppy Sweeting's relationship line
Grow every type of plant
Brew every type of potion
Use Flipendo ten times – to tip one cow or several
Complete Sebastian Sallow's relationship line
Complete Natsai Onai's relationship line
Defeat Ranrok
Subdue the Lord of the Shore
View all Pensieve memories
Wield a Deathly Hallow
Follow butterflies to a treasure
Beat Imelda's time in all broom races
Visit Poidsear Coast
Reach a combo of 100
Stun 10 different enemies using a Mandrake
Defeat a total of fifty enemies using Petrificus Totalus
Learn all spells
Save a dragon
Complete all tiers of a challenge
Upgrade a piece of gear
Meet Charles Rookwood in the Map Chamber
Spend 5 Talent Points
Find the Map Chamber as a Slytherin
Invoke Ancient Magic for the first time
Survive the troll attack on Hogsmeade
Attend your first class
Complete the introduction and finish the Sorting Ceremony