This is something that has worked on and off for a while - it was originally fixed, then it broke again and more recently has apparently been fixed.

The bug: [MC-4686][1] was fixed in minecraft version [18w43a][2] which is the first snapshot for Minecraft 1.14

Under the list of fixes for that version: `MC-4686 – Client movement when teleported`

So as long as you use Minecraft Java Edition 1.14 or later you should be able to use seamless teleportation without issue.

However, with later versions of minecraft you should familiarise yourself with the new command formats before trying the same old commands - the process of teleportation others using relative coordinates is slightly different now.

  [1]: https://bugs.mojang.com/browse/MC-4686
  [2]: https://minecraft.gamepedia.com/18w43a