Anyway to make Heartbeat happening once?

just found a way to make something happen really fast with heartbeat:connect and hmm it loops(obviously) and i have no idea in how to make this happen once each time is called as fast as heartbeat:connect.

You don't need any events to run things, just make a function and call the function. For example:

local db = false
game:GetService("RunService").Heartbeat:Connect(function(step)
	if not db then
		db = true
		--do code
	end
end)

is the same as:

function code()
	--do code
end
code()