Computer Configuration > Administrative Templates > Microsoft Edge > Immersive Reader settings
Both
HKLM\Software\Policies\Microsoft\Edge
OBSOLETE: This policy is obsolete and doesn't work after Microsoft Edge 126. This Policy is obsoleted because Picture Dictionary is deprecated from Edge as of Sept, 2023. This policy won't work in Microsoft Edge Version 127. Enables the Picture Dictionary feature within Immersive Reader in Microsoft Edge. This feature helps in reading comprehension by letting a user to click on any single word and see an illustration related to the meaning. If you enable this policy or don't configure it, the Picture Dictionary option shows up within Immersive Reader. If you disable this policy, users can't access the Picture Dictionary feature within Immersive Reader.