Several ways! One way, crush red-skinned grapes, let them soak (macerate) for a while for some of the skin pigments to dissolve into the clear juice, then press the grapes to get pink juice to ferment. Or if you want barely pink wine, press immediately.
Another process, called “bleeding” is to crush red grapes to a fermenter to make red wines. Then drain off a bit of juice that has become pink. This has the effect of increasing the skin-to-juice ratio and can make a bit more intense red wine.
Blush wines are not Rosés, they are white wines colored pink by blending in some red. Mostly not legal in the EU. The USA allows fake wines like blush, port, and California champagne.