AppleScript to create a new file in Finder (to be used in Automator)

automator_new_file.scpt

-- AppleScript to create a new file in Finder
--
-- Use it in Automator, with the following configuration:
-- - Service receives: no input
-- - In: Finder.app
--
-- References:
--  - http://apple.stackexchange.com/a/129702
--  - http://stackoverflow.com/a/6125252/2530295
--  - http://www.russellbeattie.com/blog/fun-with-the-os-x-finder-and-applescript
--
-- Know bugs
-- - When create/delete in desktop, after some time, the file is showed again and after deleted (it works, but it's strange)

set file_name to "untitled"
set file_ext to ".txt"
set is_desktop to false

-- get folder path and if we're in desktop (no folder opened)
try
    tell application "Finder"
        set this_folder to (folder of the front Finder window) as alias
    end tell
on error
    -- no open folder windows
    set this_folder to path to desktop folder as alias
    set is_desktop to true
end try

-- get the new file name (do not override an already existing file)
tell application "System Events"
    set file_list to get the name of every disk item of this_folder
end tell
set new_file to file_name & file_ext
set x to 1
repeat
    if new_file is in file_list then
        set new_file to file_name & " " & x & file_ext
        set x to x + 1
    else
        exit repeat
    end if
end repeat

-- create and select the new file
tell application "Finder"
    
    activate
    set the_file to make new file at folder this_folder with properties {name:new_file}
    if is_desktop is false then
        reveal the_file
    else
        select window of desktop
        set selection to the_file
        delay 0.1
    end if
end tell

-- press enter (rename)
tell application "System Events"
    tell process "Finder"
        keystroke return
    end tell
end tell

Open Automator and create a Service;

There is no "Service" in Catalina, but there is a "Quick Action"

The version to open file in default text editor.

-- AppleScript to create a new file in Finder
--
-- Use it in Automator, with the following configuration:
-- - Service receives: no input
-- - In: Finder.app
--
-- References:
--  - http://apple.stackexchange.com/a/129702
--  - http://stackoverflow.com/a/6125252/2530295
--  - http://www.russellbeattie.com/blog/fun-with-the-os-x-finder-and-applescript
--
-- Know bugs
-- - When create/delete in desktop, after some time, the file is showed again and after deleted (it works, but it's strange)

set file_name to "untitled"
set file_ext to ".txt"
set is_desktop to false

-- get folder path and if we're in desktop (no folder opened)
try
    tell application "Finder"
        set this_folder to (folder of the front Finder window) as alias
    end tell
on error
    -- no open folder windows
    set this_folder to path to desktop folder as alias
    set is_desktop to true
end try

-- get the new file name (do not override an already existing file)
tell application "System Events"
    set file_list to get the name of every disk item of this_folder
end tell
set new_file to file_name & file_ext
set x to 1
repeat
    if new_file is in file_list then
        set new_file to file_name & " " & x & file_ext
        set x to x + 1
    else
        exit repeat
    end if
end repeat

-- create and select the new file
tell application "Finder"
    
    activate
    set the_file to make new file at folder this_folder with properties {name:new_file}
    if is_desktop is false then
        reveal the_file
		delay 0.1
        open the_file
    else
        select window of desktop
        set selection to the_file
        delay 0.1
    end if
end tell

Add delay 0.3 line after reveal the_file to fix rename focus for newest macOS. You also need to allow Finder in security setings for Accessibility tab.

I don't think lines 30-43 and with properties {name:new_file} on line 49 are necessary (at least as of macOS Sequoia) to prevent overwriting existing files. If another file is made the filename automatically becomes "untitled 2", "untitled 3", "untitled 4", and so on.

If you want maxim-uvarov's script to have the opposite behavior for desktop vs non-desktop files (a file opened in desktop is immediately opened without being shown in the folder, while a file opened in a non-desktop folder is shown in the folder selected for renaming), then replace

-- create and select the new file
tell application "Finder"
    
    activate
    set the_file to make new file at folder this_folder with properties {name:new_file}
    if is_desktop is false then
        reveal the_file
		delay 0.1
        open the_file
    else
        select window of desktop
        set selection to the_file
        delay 0.1
    end if
end tell

with

-- create and select the new file
tell application "Finder"

	activate
	set the_file to make new file at folder this_folder with properties {name:new_file}
	if is_desktop then
		delay 0.1
		open the_file
	else
		reveal the_file
		delay 0.3
		set selection to the_file
	end if
end tell

(removing with properties {name:new_file} if you delete lines 30-43.)