Everybody has sexual fantasies (literally everybody!). Sissification isn't as common as some but is more common then others. Normality doesn't really apply but men wanting to be softer and more stereotypically feminine is very common. Sometimes this will mean submission, sometimes feminization (forced or by choice) and sometimes sissification (and sometimes all three!).
Look at how many subscribers sissy Reddits have (including the Academy Reddit), do a search for "sissy" on PornHub or xVideo and see how many results you find. You're not alone!