Edit>Paste as>New image or File>Create>From clipboard will do what you are looking for. Same function under two different names, so same shortcut: Ctrl-Shift-V.
Note that if you paste as a layer, you can do Image>Fit canvas to layers to have Gimp shrink-wrap the pasted layer.
The free key-remapping product
can resize a window to an exact size.
The following AutoHotkey script will resize the currently active window to
1280×720 pixels when F9 is pressed:
F9::WinMove, A, ,,, 1280,720
After installing AutoHotKey, put the above text in a .ahk file and double-click
it to test. You may stop the script by right-click on the ...
You may emulate a device with a small screen, such as the iPad.
All websites that are designed to work with small screens will then act accordingly.
Here are a couple of Chrome extensions that might help:
User-Agent Switcher for Chrome
Mobile View Switcher
The following post is highly upvoted but didn't work for me:
How can I view the mobile version of a ...