e4 d5 response?

Take the pawn.

If they play Nf6, play Bb5+ and if they respond Bd7, play Be2, then develop normally and let them have the pawn back.

If they play Qxd5, play Nf3, then if they play Qa5, play d4, Nc3, Bd2 and try to castle Q-side quickly. If they play Bg4, chase it away with pawns. Qxd5 and then not Qa5 is a bit too rare to worry about. The theory for ...Qd6 gets a bit complex.

That is the Scandinavian defense If you're the one playing it: Then I'd reccomend to put the queen to a5 or to go back to d8. Just don't hang out with the queen in the middle when it's still in the opening because it can be attacked with the opponent also developinf so it could result in an development disadvantage. How to play against it: Take the pawn and when the queen takes back it is generally a good idea to immediately attack it with Nc3 forcing it to move and waste time getting the queen to safety. If the opponent checks in the e-file block it with the bishop. Blocking with the queen is generally not the best move because it blocks the bishop's. Natural way to develop.

If you like gambits, you can play this

E4😃

If you like gambits you can play this:

If you like gambits, you should play this:

You should also play the same if you don't like gambits.

Else, the Scandinavian would the the refutation of 1.e4.

Take the pawn and go from there.