I am new to adobe after effect and photoshop please tell how to make text stroke or text outline blink means flash . open this below link to get more about what i am asking Intro for Carry Minati - YouTube
Use a duplicate layer, animate the opacity.
Or they might not be using the text's native stroke at all.
It could be a Text Animator stroke color>opacity (which does require the text's native stroke be enabled, image below)
or a Layer Style stroke
or the effect Generate>Stroke
All of those will give you control of stroke opacity.
Not sure which is the most efficient.