How to open Chrome Portable with predefined window size? (HELP)

I'd use a window manager to handle that. Windows 10 can do it in halves. I think Windows 11 can do quarters now. A third party window utility could help, too.

http://brianapps.net/sizer4/ It can be used as a portable, I use it that way myself but I'll leave you figure out how.

(1) Goto http://www.brianapps.net/sizer4/

(2) Download the "binaries only" zip file of Sizer

(3) Unpack the zip file to a folder of your choice (let's say "W:\Sizer")

(4) Launch Sizer.exe

(5) On launch a folder "Sizer4" will be created in the %appdata% location on your system. If you are not sure where that is read this https://www.lifewire.com/find-and-use-the-appdata-folder-in-windows-4771752 In any case, open that folder.

(6) Right click on the Sizer icon in your System Tray and select to "Configure Sizer..."

(7) In the dialogue that opens up click on the Load/Save tab. Then click on the "Apply" button. Sizer will create a file titled "sizer.xml" in the %appdata% Sizer4 folder. Click on the Okay button to exit the dialogue.

(8) Copy the file sizer.xml from the %appdata% location into the W:\Sizer folder you created in step (3) above.

(9) Right-click on Sizer in the System Tray and choose Exit.

(10) Now launch Sizer again and you will find that it will use the configuration file sizer.xml in the location W:\Sizer

The long and the short of all this is that if Sizer finds a configuration file (sizer.xml) in the same folder that sizer.exe is launched from it will use that configuration file (not the file in %appdata%) and hence you have made your Sizer a portable application. If that is what you want you can delete the Sizer4 folder in %appdata% as you don't need it now, or you can leave it in place, it won't do any harm. Just remember that now when you make your own custom window size configurations to Sizer that it will save your custom configurations in the sizer.xml file that is located in W:\Sizer.

It's a great little program Sizer, have used it for years.