>>22239777
It does a bit because the thin part still has some width, and on some plugs it can be wider than on others.
In general, the plugs are used for three things: to arouse people if they have kink on it, to create additional pressure on prostate (by men) and the legs of the clitoris and vagina (by women: if you enter women's vagina while her ass is plugged, you can actually feel the plug through the vagina walls, and this can add to her sensations), and to prepare someone for anal sex by actually relaxing the sphincter muscles. In the third case, to actually have some effect, you (in most cases, however it can vary widely) need to use ~from 2 to 4 plugs, increasing the size after ~20 minutes in. From personal experience, after the third plug (4.5cm in widest place, ~2.5cm in the thin part) it's easier to enter and girl gets a lot less discomfort, however, if you'll use only the small ones (most common in this thread, 2.8cm and ~1.3cm in the thin part), the difference from just entering without any plug-prep would he almost non-existent.
*And of course, this all applies only to cases where water-based lube is used generously
