So, I tried moving smoothly moving model through Part and it doesn't work, here's the script. So IDK another way to move the model.

local Portal = game:GetService("Workspace"):WaitForChild("RealmTP")
Pos2 = CFrame.new(458.969, 19.581, 946.224) -- Position of the Portal in air
Pos1 = CFrame.new(458.969, 16.571, 946.224) -- Portal Ground position


local TweenService = game:GetService("TweenService")
local TweenAGoal = {}
TweenAGoal.Position = Pos2
local TweenATime = TweenInfo.new(2.5) -- Time to be doned

local TweenBGoal = {}
TweenAGoal.Position = Pos1
local TweenBTime = TweenInfo.new(0.7) -- Time to be doned

local TweenA = TweenService:Create(Portal, TweenATime, TweenAGoal)
local TweenB = TweenService:Create(Portal, TweenBTime, TweenBGoal)
for i,Player in pairs (game:GetService("Players")) do
	local Database = Player:WaitForChild("Database") -- Waits for Database inside Player
	Database:WaitForChild("Value_Inv"):WaitForChild("CompletedZombie").Changed:Connect(function()
		if Database:WaitForChild("Value_Inv"):WaitForChild("CompletedZombie").Value == true then
			
			TweenA:Play()
				wait(2.5)
			TweenB:Play()
		
			end
	end)
end