There are a few ways to make an A4 size in Photoshop. One way is to use the Document Size command in the File menu. This will let you specify the size of the document in inches and pixels. Another way is to use the Scale command to resize the document while preserving its proportions.
To make a poster-sized file in Photoshop, you can use the “Poster Size” tool. This will create a file that is the same size as a poster board.
A4 is a standard size for most printers.
There are a few different ways to do this. One way is to use the “Poster” option in the “Image” menu. Another way is to use the “Image Size” option in the “Image” menu, and then enter the desired size in pixels.