It seems you won’t let this deniability thing go so why don’t you just do the following …
Install EndeavourOS with the GUI installer and choose “Encrypt”. You will end up with a standard full disk encrypted system.
In this LUKS-encrypted system you can mount, create and modify VeraCrypt containers (from the usual GUI you know from Windows). Yes, you can actually even use the hidden container feature of VeraCrypt in Linux. (Here is a link about TrueCrypt on Arch, but it also applies to VeraCrypt).
Install VeraCrypt by typing this in a terminal …
sudo pacman -S veracrypt
So you could give up your EndeavourOS password and your VeraCrypt container outer password and still have data in the hidden part.
Voila, I think that’s what you would consider as plausible deniability.
You can read about LVM here, but I would advise you just to forget about them at this stage of your knowledge.
All? You’ll never get to install then
Seriously, just go with steps 1. and 2. right now. (Next install you can then maybe go for LVMonLUKS etc.)
(Here’s some general information regarding luks)
To keep it simple:
LUKS is basically dm-crypt with a luks header. In this header some information (keys, etc.) is stored. One can actually look at the encrypted data and know that it is luks-encrypted. So this certainly isn’t deniable encryption.
But you could store and access the luks header someplace else, for example a USB-stick, which leaves you with pure random data on your encrypted partition/drive. Just as pure dm-crypt would give you. This could be considered as deniable encrytion.
Nobody could prove with certainty that they are looking at encrypted data and not random data.
But let’s get real. What else would a couple of GiB up to TiB of “random data” be, other than encrypted data. And with SSD’s becoming the standard, well, filling a ssd with random data to delete/shred data just isn’t necessary and actually really stupid. I certainly wouldn’t believe you if you told me you weren’t hiding data.
If you actually mean the hidden container feature of VeraCrypt when talking about plausible deniability, then no, this isn’t a standard feature of LUKS.
But if you read up on the links I provided in my earlier posts you will see it can be done. Just not per GUI and it may be a bit complicated for someone not used to the terminal and without any knowledge of the Linux filesystem etc.