Acrylic ... Can someone help please ...

[ghostwriteruk]

I recently began knitting my first garment after about thirty years. It's nearly finished. I wanted to join two pieces and the pattern said ... press each piece under a wet cloth', I did this and thought the knitted pieces looked a bit thinner. Today I read the instructions on the balls of wool. They said 'never wet press this wool.' The wool is acrylic. Is it possible to recover in some way? If I wash it in soapy water would this be a good idea? Will it make any difference?
Thanks for the help if anyone can ...