A sort of 3-4-1-2 would be the best for them. But there are too many gaps and no cover if something goes wrong to the few who are ok:
------------------------Leno*------------------------
---------Holding-------New CH------New CH--------
Bellerin------Guendouzi/Torreira***---New CM------Tierney
------------------------Özil-------------------------------
----------------Laca---------Auba-------------------------
*I don't really like him, never have but you can't change absolutely everything overnight
** You can only realistically play one of them, alternating alongside a proper partner would be ok, Ceballos is probably not that man as it stands
So at least three high profile signings, then you need everyone to stay fit all the time because nearly everyone outwith kids (Nelson, Saka, Willock, Smith-Rowe, Martinelli - could all go either way) that I haven't included there (AMN, Kolasinac, Sokratis, Luiz, Xhaka, Mustafi, Chambers, Martinez etc) aren't good enough for a club like Arsenal, it also means that there's no room in the starting XI for Pepe so that looks a colossally stupid move.