Is there a way to get out of the tutorial zone without the glider?

This is impossible. Even if you manage to get past the fog, the paraglider check is hardcoded in the Player object code.

The code looks like this:

if ( !sForceEnableGlidingAndSurfingAndGiveRupees && !sIsDungeon )
{
  if ( !hasParaglider(0) && 
       (x < -1600.0 || x > -350.0 || z < 1400.0 || z > 2400.0) )
  {
    player->field_2304_x = -1021.7286376953125;
    player->field_2308_y = 253.31527709960938;
    player->field_230C_z = 1792.6009521484375;
    // 奈落開始待ち translates to 'wait for abyss start' (= the voidout state)
    return AI_AIBase::changeState(this, "奈落開始待ち", 0LL);
  }
}

(If you want to see for yourself, this is at 0x710082EFE4 in version 1.5.0 on Switch.)

Unlike Wind Waker's castle barrier, this time there is no collision or object you could clip through. It's a simple coordinate check that always runs and there is no way to glitch past this check since it is embedded in Link's actor code.

No, it is not possible to leave without the glider. As mentioned by multiple users in this thread, the glider is not necessary to descend, however, the fog that prevents you from leaving will not dissipate until you obtain the glider. That is, once you've already obtained the glider, it seems that you can descend the plateau without it, but you can't avoid actually getting it.

The real problem is not physically leaving the Plateau, it's the fog that makes you despawn. The paraglider removes the fog, this video doesn't leave the Plateau (the map is available both at launch and landing)

Have you even played the game? You cannot leave the plateau without completing the first four shrines and obtaining the glider. Its not the height of the plateau that stops you leaving, its the invisible barrier of fog surrounding it.

The video that spawned that particular discussion is here, and even there, the person who posted the video commented that this does not negate the need for the glider:

Nah. You need the glider to despawn the void out area around the plateau. If you could get past that you can skip it.