Girlies, do u know any hack to hide armpit fat in a sleeveless dresses?

I am wearing this lovely sleeveless dress (size 12/14) I found in a thrift store for my graduation, but it's a little fit (usually I buy UK 14) and I feel a little uncomfortable (it's a process, right?). I live in the UK and I want something like a quick fix/hack. Maybe I can buy boob tape, but still not sure if that will work. Lmk what u guys think :)