How to get inside the basement storage solo: move the box to the wall, place it vertically. Switch to first-person mode. Jump on the box, press the W + D buttons and turn the mouse to the right. There is a chance to go through the wall and take the gold solo.
If the box disappears or broken, go away from the spawn of the boxes and come back. The boxes will appear again.
GTA Online The Cayo Perico Heist.