How do you get the children's of the children's in workspace?

:GetChildren() returns a table. That's not what you want. You want to call :FindFirstChild() on the Part itself. Also, LobbyCount[i] == v.

So:

LobbyCount = game.Workspace:GetChildren()
for _, Part in pairs(LobbyCount) -- If you use logical variable names, this code gets easier to read and debug
    if Part:FindFirstChild("PointLight") then
        Part.PointLight.Enabled = true
    end
end

Here ya go

local items = {}

function Scan(item)
    for i, v in pairs(item:GetChildren()) do
    print(v.Name)
    table.insert(items, v)
        if #v:GetChildren() > 0 then --Check if it has more children if so then Scan() again
            Scan(v)
        end
    end
end

Scan(game.Workspace)

--This will scan everything inside Workspace

for i, v in pairs(items) do --Get every object in the `items` table then set the pointlight to true
    if v.Name == "PointLight" then
    v.Enabled = true
    end
end