tech (ubuntu) question@phseiff you can't (what type of file?) unless you put templates in $HOME/Templates, in that case there's a menu "New Documents" and selecting one will just copy over the corresponding file from the Templates folder
tech (ubuntu) question@quinn@phseiff the whole template system, dolphin doesn't require you to fill that up by yourself, it just lets you create the file that you need
tech (ubuntu) question@jeder@phseiff i think it might also fetch that from other XDG paths (/etc/xdg/Templates maybe?), maybe the OS is also supplying those templates in some cases
otherwise i wouldn't know how the file manager would know file formats
tech (ubuntu) question@quinn@jeder i mean, for plain text file formats (or more specifically, file formats where "empty/new" files are actually empty text files w/ a specific ending, it might be useful to have an option to create a new empty text file and fill in name and file type oneself, but apart from that the file explorer rlly can't predict what kind of file types might exist on the systems and what new files look like for them