Concreting the pedestal

Hello,

I still have to concrete a platform at my front door (38 cm high, and then another 12.5 cm for a step).

I have a frame doubling at the front door.
Do I concrete up to the frame doubling now, and will it withstand the pressure from the concrete without warping (there is nothing on the outside yet),
or do I have to insert insulation strips like with screed?

For me, it is like this: my front door is 78 cm higher than the first step in the staircase,
now a platform is supposed to go there,
the ground floor has already been completely blasted out,
but I think if I screw iron bars into the wall and into the stairs, and lay two iron meshes in the concrete layer,
you can't go wrong, right?

And if I concrete the first platform to 38 cm,
and then another 12.5 cm on top,
then it should fit exactly, right?

There is no screed strip between the concrete and the wall, right?

And if I am then 2 cm below the door sill with the concrete height, it will fit exactly when I lay tiles on top, won’t it?

Thanks, best regards