How do I make a model move? ( Advance Help needed )

Ok, the title of this makes me sounds like a beginner, but that's not the case in this situation. I know that you can just change the CFrame of the part every 0.1 seconds or stuff like that. But what I need is something better, don't tell me to use Translateby or BodyMovers because I'm pretty sure that wouldn't work either.

Ok, so what I want to know is how they animated the train in JailBreak or the moving parts In Tower Of hell or any moving object In any other good game.

BodyForce would work great if only you could make the part anchored, but you can't. I need something That makes the part move smoothly, something that doesn't make the part look like its laggy on other devices, something you can step on and move along with.

if only BodyForce could be applied to anchored parts :(

Thank you for your time!

AlvinBlox did a good video on TweenService

There's a function called MoveTo, if you use vector3 with it, you can move it anywhere! You can loop it using while true do, or maybe repeat until. Explanation: https://developer.roblox.com/en-us/api-reference/function/Model/MoveTo

Code:

local Model = game.Workspace.Model -- Your model here
while true do-- If you want it to loop
wait(.1) 
    Model:MoveTo(Vector3.new(0, -0.1, 0)
end