Hey, I just downloaded endeavourOS with i3. I have no experience with arch nor these kind of window managers before so it is a bit of a struggle for me.
If I understand it correctly, it seems to create a new workspace for different things, such as one for web browers, terminals, file systems, etc… and these can be navigated with [mod] + 1,2,3,. The issue that I am facing is that with intelliJ, the application seems to share the same workspace as the other terminals which is very annoying since it really limits how much I am able to see. I understand that you can fullscreen a window with [mod] + f but is there no way to instead create a completely new workspace for intelliJ when I open it to keep it separated from the terminals?
Also is there a way to change it so that the windows dont share the exact same size? I saw a video of another window manager where the child window is the size of the parent 1/2 each time rather than having every window being the exact same size.
I don’t use i3 or IntelliJ myself, but from this and more specifically this: “To move a window to another workspace, simply press $mod+Shift+num where num is (like when switching workspaces) the number of the target workspace. Similarly to switching workspaces, the target workspace will be created if it does not yet exist.” There is also a lot more info in there about changing window sizes and also " 4.17. Automatically putting clients on specific workspaces". Hopefully this gets you moving in the right direction. Feel free to ask whatever else you come across, there are a lot of i3 experts around that know way more than I do about it.
Once you open IntelliJ, press “Mod + Shift + 8” to move it to 8th workspace. Of course you can use any number workspace you want. Need not be 8.
You can also switch to a new workspace with Mod + <number> and then launch IntelliJ.
It is also possible to bind it to a specific workspace so that it automatically moves to that workspace when launched. Add this to your i3 config and replace “CLASSNAME” with the actual class name of IntelliJ. You can find that using xprop. Also, you can replace ws8 with a different one to bind to a different workspace number.
I rude 
Forgive me i no welcome you to EndeavourOs forum…