Blocks can't be placed on the age like on Bedrock edition

In Bedrock you can place blocks simply by looking at the place you want the block to be at

 

https://youtu.be/Q5lcPRl9qZ4?t=17

 

In Java edition, you first need to go to the edge, hold shift, go over the edge until you can see the edge you want to place the block next to.