Liesl & Co patterns–sized by RTW or by pattern sizing?

I just last night had the realization that in pattern sizing, I'm not the same size I am in RTW. I have mostly sewn for my 2 year old or costumes from non-standard patterns, so this is a shock. I have not yet tried to sew anything from a Big 4 pattern for me, but I had just started tracing a skirt from Simplicity when I had a niggle about double checking size. I've sewn the Liesl & Co. Everday Skirt and used a M, which corresponded to my usual 10-12. It fits fine. So...can I rely on these patterns to be true to RTW sizing? (I ended up falling down a rabbit hole of message board posts on various forums filled with people ranting about the weird pattern sizing)