To create a 'full' project board, the project must first have been added to the project portfolio in the 'Proposed' stage. This is the same process for moving projects through the stages on the Portfolio board later but first you myst move it to concept.
The 'full' board is created automatically once the project progresses to 'Concept'
To do this, click the three dots to the left of your project, select MOVE TO... and then MOVE TO GROUP...
Pick the 'Concept' group (even if it's actually further on, you must first pick concept)