If $\Omega$ is an open Lipschitz domain with bounded boundary then their exists a continuous operator $E: W^{s,p}(\Omega) \rightarrow W^{s,p}(\mathbb{R}^d)$ where $s\in (0,1)$ such that $Eu=u$ on $\Omega$.

A similar result holds for integer order Sobolev spaces.

But in case of integer order sobolev spaces one always has the existence of a continous extension operator $E: W_0^{k,p}(\Omega) \rightarrow W^{k,p}(\mathbb{R}^d)$ regardless of the regularity of $\Omega$ e.g. the zero extension.

My question is, if $\Omega$ is only open, do we also have the existence of a continuous extension operator

$$E: W_0^{s,p}(\Omega) \rightarrow W^{s,p}(\mathbb{R}^d) \text{ where } s\in(0,1)$$

If yes, can someone suggest literature where this is mentioned?

Honestly, I don't want to bother trying to prove it myself, or rather, I would like to have at least assurance that this is true first.