Get quoted string

@echo off

REM Get a quoted string from a certain line inside a file

REM The string is the 2nd string enclosed by doublequotes, so we use tokens=4

for /f usebackq^ tokens^=4^ delims^=^" %%A in (`find ^"VTOY_DEFAULT_IMAGE^" F:\ventoy\ventoy.json`) do set isop=%%A

echo ISOP: [%isop%]

We must use the special backquote character  for the find command.