Oh, yes, they’ve changed over the years!
Lets take a look at a few....
A chemise—could also be called a shift, an under-gown, or smock, depending on the period. They were of varied length, most common were either knee or ankle lengths. Could be sleeveless, or have short or mid-length sleeves, depending on the garments they were made to wear beneath. Also, dependent upon the season, they could be made of various cloth, light for warmer weather and heavier materials for the winter months.
A chemisette was much like a sleeveless 'false shirt', however another version was much more like a camisole, usually waist-length, and often was gathered (had a string tie) a couple of inches above the hem. Dependent upon the style of dress, a chemisette could be mid-thigh length. Shorter and loose flowing ones with matching ‘tap’ pants, often made of cotton and silks, became the ‘underwear’ for women in the 1920’s. These are what gradually evolved into bras and panties.
Corset (also called stays) came in various styles and lengths. Their purpose was to ‘shape the body’, mainly make the waist smaller and the hips more prominent. They often flattened the breasts rather than enhanced them. The sleeveless waistcoats of the 1700’s look a lot like corsets, but were worn as an outer or top layer rather than underclothes.
Pantaloons and drawers (men’s versions were also referred to as drawers) were crotch-less and very loose fitting. Pantaloons would have a ruffle near the ankles that could be seen beneath the skirt. Drawers would have ties near the knees.
Slips and petticoats were worn beneath the dresses to add volume and hold the shape of the skirt. Hooped skirts/slips, had wire sewn in them, which again, made sitting rather impossible.
Men had braies, and drawers. Braies were little more than lengths of fabric pulled up between the legs and tied around the waist. Later ones had waist band and ties in the front. Drawers were usually knee length and tied at the waist.
Like the bustles and bum-rolls, men had things to enhance their bodies too. Cod-pieces had padding and tied around the waist, and calf-pads were strapped around their legs to make their calves look more muscular.
Union suits were both long and short. The top and bottoms were connected. It was during the 1920’s that the two became ‘disconnected’ and men started wearing garments closer to T-shirts and briefs.
Just a note....there were many variations to all of the above!