how much grammatically is this sentence true ?

remove 'is'.

grammatically done
Hi,
I wonder what made you think about this sentence, or where you read it!!
A couple of words taken away and if you phrase it again,...it sounds good.
It should be....
If your face tends to be heavy at the jawlines, any style adding more bulk to that area would not be preffered.

thank u sir. This part of my schedule to be accurate about that.

agenda
agenda vs. schedule

Depth's refrasing seems good to me, however I would add that "jawline" does not need an s at the end.