when I have lots of seams all coming together in one spot I tend to press the seams open. I use a ???pressing rod like esparys described (although I purchased mine ). Or you can do like Rob says and hammer them down--I mist first and then use my 3lb plastic coated hammer.

You need to get a little sewing wedge, of course there are gadgets you can buy, but it’s easy enough to make one out of scraps of fabric https://www.youtube.com/watch?v=VahPOp5bY6k
https://m.youtube.com/watch?v=U91iJMKJ23g

Pressing open or grading your seams will help reduce bulk.

When PP I always press my seams from one side to another or open when instructed by the pattern. I use Carol Doak's PP method which keeps down the excess fabric and paper when working on the blocks.