My ps4 storefront is Spanish and can't change it to English to make purchases in the Ps4 store. so my question is: If I preorder a game in my Spanish storefront will I get the game in English or Spanish? I hope this makes sense.
That depends on the game.
Most games feature multiple languages, with the notable exception being Japanese games, which usually only feature Japanese (with some few exceptions also including English, and nothing more).
If you're using the Spanish (Spain) storefront, chances are you will be getting the European version of the game, which will probably include German and French (and with very high likelihood English too).
If you're using the Spanish (Latin America) storefront, chances are you will be getting the American version instead, which will likely include English and French as well.
Some games only have an international version, in which case they'll include all supported languages, regardless of which storefront you buy them from.
So, while it's very likely your game will support English, there is absolutely no guarantee it will. It's different for every game.
As an anecdote, I've been buying games in the Swiss German storefront for decades, and have only encountered 3 games that didn't support English: Deus Ex: Human Revolution (PS3), Wolfenstein: The New Order (PS3, German edition), Wolfenstein II: The New Colossus (Nintendo Switch, German edition).
Wolfenstein is one of the few games, where the German version is completely separated from the rest of Europe, due to Nazi references being illegal until very recently.
I have yet to encounter a PS4 game, where English isn't included in the European version.