How do I correctly use Delta Time?

I'm working on an FPS game and one of the big problems is uncapped FPS for I use RenderStepped for pretty much everything in the Framework as well as other things. I realize this is bad practice for those such as myself wanting to play the game in a higher FPS but after reading a lot and a lot about Delta Time I just can't understand it, here's a code that I tried but it does nothing and I really just don't know what to do.

How it looks in 60 FPS

How it looks in 240 FPS

run.RenderStepped:Connect(function(deltaTime)

	local originalDeltaTime = deltaTime
	while deltaTime < 1/60+1/((1/originalDeltaTime)+4) do
		deltaTime = deltaTime + game:getService("RunService").RenderStepped:Wait()
		secrecoil()
	end
end)


function secrecoil()
	
	if cam:FindFirstChild(secondary.Name) then
		
		if secondary[secondary.Name].Flame.ParticleEmitter.Enabled == true then
			
			local random = math.random(2)
			
			if random == 1 then
		
		for i = 0,s.recup, .1 do
			
			camcf = camcf * s.recoil
			run.RenderStepped:Wait()
			
		end
		
		for i = 0,s.recdown, .1 do
			
			camcf = camcf * s.recoil2
					run.RenderStepped:Wait()
			
		
		end
			
		elseif random == 2 then
		
		for i = 0,s.recup, .1 do
			
			camcf = camcf * s.recoil3
					run.RenderStepped:Wait()
			
		end
		
		for i = 0,s.recdown, .1 do
			
			camcf = camcf * s.recoil4
					run.RenderStepped:Wait()
			
		
		end
			
			end
		end
	end
	
end

Anything would be helpful at this point. I wanna future proof this game and this is one of the big steps I gotta take.

The usual way of making things framerate independant is to scale your movement by deltaTime. For example:

local speed = 20
local part = workspace.Part

RunService.RenderStepped:Connect(function(deltaTime)
	-- Multiplying by deltaTime here makes the movement framerate invariant 
	part.CFrame += part.CFrame.LookVector * speed * deltaTime
end)

If you just wanted to run a function roughly n times every second, then you could do it like this:

local elapsedTime = 0
local rate = 1 / 30 -- 30 times a second

RunService.RenderStepped:Connect(function(deltaTime)
	elapsedTime += deltaTime
	if elapsedTime >= rate then
		-- Run function here
		
		elapsedTime -= rate
	end
end)