A traditional method is tying. I have found this method on many pillowcases, often more than 200 years old.
For this purpose, ribbons of sufficient length are attached in the same position at the lower edge of the front and back part of the pillow and tied in a bow.
The strips were usually made of the same fabric as the pillowcase. Bobbin lace ribbons were also used in some examples. These are thinner, usually smaller and therefore not as bulky. They also have an additional decorative effect.
Depending on the firmness of the cover fabric and ticking used, as well as the stability and width of the ribbons used, the bows under the put up cushion are more or less visible.