Either you haven’t picked up the horn at all in a stretch or you haven’t picked up your alto and mostly play tenor.
To sharpen up on tenor and you usually play alto or soprano when you usually play bari, the best thing you can do is long tones.
They get you reacquainted with the horn and more in touch with the subtleties that exist between the kinds of saxophones and the details about playing your particular horn and mouthpiece.
It works the same way if you play other wind instruments- flute, clarinet, etc.
Doing a bunch of long tones on them will get your sound where you want it to be.
At a sax clinic, Paul Contos talked about just doing long tones for about a week and a half if you’ve never done something like that before.
It will help your sound.
And if you need to get back to speed quickly on a horn, work on them!