If you open up your InLoopOut compound, the Sequencer has a couple of outputs you may have interest in.

For e.g. if you want a trigger when the sequencer reaches marker #2, you can do this:

You can use Running to do something if sequencer starts or stops running.

Or you want a trigger when restart occurs:

And so on.

Regarding the usage of the trigger you get. It depends what do you want to achieve.
For e.g. if your texts are in a text file then you can increase a line index one by one using the trigger:

I think there is a problem which is the text changed when sequence move from loop marker to out marker

but I need the text change after out mark and before in marker

How to fix that?

I think that I get the results I needed by adding new marker in the end of animation then set B value to 3 in equal module 

But I have noted There is no scale option like position and rotation in lower third compounds so how to do such scale animation using sequencer

You can use an additional Sequence Node like this:

But before that please delete all curves from the original LThird tracks if any, and use Sequence Node's tracks exclusively to do all the animation of the LThird element.

But your request is noted, we'll expose Seq Scale as well in the future releases.