How to get light to "bounce" or actually BE casting indirect light

See screenshot below I have a direction light in my scene, which is supposed to represent lightning, it is only on breifly, but I need it to “bounce” and light up a room as well. How do I do this?

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I thought it might have something to do with baking but I hope not because if I make any light “baked” it simply acts as though I have deleted it and isnt shown in the game.

BUMP Still need help with this please!!