The odds available at the moment, at least Real Sociedad is still quite favored although indeed, it seems it will be difficult for Manchester United to get a good result in the away game in the first leg later. But even so, there will be two legs that Manchester United will probably make a good effort to get a draw in the first leg, and then will target a win at Old Trafford for the second leg later. But indeed, the scenario of losing and winning will certainly happen and Amorim should be able to maximize the match in the Europa League after getting a series of bad results in the domestic league.
It most likely Sociedad is gonna win it. That's caused by i'm not so confidence with Manchester United's odds. it went from 2.85, then probably closed above 3.00, which is significant enough. I believe many also have the same thought like you.
As for the bet, and i prefer to take both team to score. I'm not denying Sociedad to win the first leg, but to be fair, Manchester United has chance to score as well. However, my concern for Manchester United is that they will play without some key players such as Amad.
It makes me skeptical with them to win the game, then i predict the game will end with 2-1.