How big is Stormblood?

Since i'm new to the game and a new expantion was being released, i said:

"I'll just go get the last expansion, because it comes with everything".

Silly detail is that it comes with everything after the release of the newest expansion, which means that right now i have the bonus for pre-ordering ShadowBringers, but don't have access to Stomblood's content.

So after the new expansion is out, i'll be able to play Stormblood, and i assume i need to play it to get the levels to reach Shadowbringers content, so how much content i'll have to rush through to get to the newest expansion?

Well, if you want just raw numbers insofar as the number of Main Scenario Quests are in Stormblood. 122 quests, then 40 patch quests before Shadowbringers, for a total of 162 quests. This includes 8 mandatory dungeons, and 4 mandatory trials. Not including side content and optional dungeons and trials.

"Have to rush through" seems to be horribly wrong. The entire point of this is to be entertained. More than the not-yet-released expansion is entertaining. Take your time. Enjoy it.

In general, though, each expansion has been larger than the previous.

And no one specifically said it but 10 levels. Of course, doing all those quests/dungeons/etc should more or less take care of that part.