How do I view achievements in minecraft?

From the Minecraft Wiki on Achievements:

Achievements are tracked per user account. They are not tracked separately per world; achievements earned in one world apply to all worlds using that edition and that user account. On most platforms that Bedrock Edition runs on, achievements are logged to an Xbox Live account, and so players have to be logged in to their Xbox Live account to earn them. On PS4, Bedrock achievements are logged as trophies to the player's console account, and if logged into a PSN account and online, they are synced with PSN but not Xbox Live (even if logged into an Xbox Live account).

This means that you can find them on your Xbox account. You can root around the Xbox website under your account until you find a page that looks like this:

Then just scroll down to view your achievements!

Go to Profile in the menu and you will see the achievements button. Press on it and it will show all your lifetime achievements.

In Java Edition, press L and you will see your world achievements. Or hit esc and press the achievements button.

I hope this is useful to you.