There isn't a yes or a no that anyone could in general answer to your question.
Some companies (like One Stop DIY
shop here in the US)...carries a line of One Stop Flavors and One Stop Blends...that you DO use singly, to make your
eliquid. They have ones like Strawberry Milk, Blue Raz Slush, Baked Cinnamon Roll, Lotta Latte, Oldtyme Rootbeer, and many more. You simply add usually between 4-10% of 1 of those to your own PG, VG, and nic base. They're wonderful, too, when you make them! Many of us on the ECF buy them.
So, if I wanted to make a Baked Cinnamon Roll
eliquid...I'd be perfectly happy to use
their single flavoring to make it...rather than 5-6 other flavorings combined to make it.
But,
no one can tell you if the particular brand of apple pie concentrate (flavoring)
you're thinking of using...will have the same great result as OSDIY Shop's Flavors & Blends do.
I'd suggest buying a very small bottle of the single concentrate and trying it first. If it tastes great when you make it...you got your answer! If it doesn't...then find a recipe for Apple Pie, buy the individual flavorings needed to make it (in small sizes), and give IT a shot.