The path to the New Doc Sizes.json or MRU New Doc Sizes.json file is user account related and Photoshop version specific and similar to the following...
MAC:
/Users/<user>/Library/Preferences/Adobe Photoshop 2021 Settings/
Win:
C:\Users\<user>\AppData\Roaming\Adobe\Adobe Photoshop 2021\Adobe Photoshop 2021 Settings\
EDIT:
As this directory may be hidden, you may find the following scripts helpful:
https://github.com/MarshySwamp/Backup-Photoshop-Settings-System-Info
/* Open Photoshop Presets & Settings Folders - Universal */
#target photoshop
app.bringToFront();
openPresetsAndSettingsFolders();
function noteOne() {
alert("This script will open 3 folders to facilitate backing up data before updating or migrating Photoshop.")
}
function noteTwo() {
alert("Script completed! Backup the following files and folders:" + "\r" + "\r" +
"* Actions Palette.psp file inside the User's Settings folder" + "\r" + "\r" +
"* All folders inside the Application's Presets folder" + "\r" + "\r" +
"* All folders inside the User's Presets folder")
}
function noteThree() {
alert("Note:" + "\r" + "In addition to backing up the Actions Palette.psp file, it is strongly recommended that each action set is saved to individual .atn action files!")
}
function openPresetsAndSettingsFolders() {
var os = $.os.toLowerCase().indexOf('mac') >= 0 ? "mac" : "windows";
if (os === 'mac') {
// alert("It's a Mac!");
noteOne();
noteTwo();
noteThree();
appSettings();
appPresets();
userPresets();
function appSettings() {
var appPath = app.path.fsName.replace(/^\/.+\//, '');
var userSettingsDir = '~/Library/Preferences/' + appPath + ' Settings';
var userSettingsDirOpen = Folder(userSettingsDir);
userSettingsDirOpen.execute();
}
function appPresets() {
var presetDir = app.path + '/Presets';
var presetDirOpen = Folder(presetDir);
presetDirOpen.execute();
}
function userPresets() {
var appPath = app.path.fsName.replace(/^\/.+\//, '');
var userPresetDir = '~/Library/Application Support/Adobe/' + appPath;
var userPresetDirOpen = Folder(userPresetDir);
userPresetDirOpen.execute();
}
} else {
// alert("It's Windows!");
noteOne();
noteTwo();
noteThree();
appSettings();
appPresets();
userPresets();
function appSettings() {
var appPath = app.path.fsName.replace(/^.+\\/, '');
var userSettingsDir = '~/appData/Roaming/Adobe/' + appPath + '/' + appPath + ' Settings';
var userSettingsDirOpen = Folder(userSettingsDir);
userSettingsDirOpen.execute();
}
function appPresets() {
var presetDir = app.path + '/Presets';
var presetDirOpen = Folder(presetDir);
presetDirOpen.execute();
}
function userPresets() {
var appPath = app.path.fsName.replace(/^.+\\/, '');
var userPresetDir = '~/appData/Roaming/Adobe/' + appPath + '/Presets';
var userPresetDirOpen = Folder(userPresetDir);
userPresetDirOpen.execute();
}
}
}
https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html