The First Step of The Blockout:

For my blockout, i started by using the Cube grid tool in Unreal Engine 5's Modelling Mode and made an L shape layout and added in rooms which can be seen below

For the modelling stage, i started with the player's start location and added it in a broken part of the building which has a broken roof which doubles as a small staircase up to the floor above. (see image below)

I then added a one way valve which forces the player to be kicked out of the starting area (see above image near checkpoint)

The Main Corridor:

For the main corridor of the level i added two small rooms before getting to the platform sequence in order to diverse the level a bit and i then added locked room by the platform stage as well as a storage room on the right, just before the platform sequence

I added a small storage which contains a few crates as well as a key to the locked door by the platform sequence in the great hall

At the end of the great hall and added a small platform sequence seen below

The End Sequence:

After the player has used the small platforms to traverse to end, the player will find a door that they can access to reach the end of the level

The End.

That concludes everything i have made for this 3D Blockout however i have added a small video at the end of this post which contains a walkthrough of the level