A flat red or pink facial patch present from birth, persistent, painless, and non-itchy is often a capillary malformation, also called a port-wine birthmark (nevus flammeus). These differ from infantile hemangiomas, which commonly appear or enlarge after birth and may later shrink. Port-wine birthmarks usually persist and can become darker or thicker over time. DermNet overview

Because it is on the face, arrange an assessment with a dermatologist, ideally a pediatric dermatologist or vascular-birthmark clinic if this is a child. It is particularly important to be assessed promptly if the patch includes the forehead, upper eyelid, or area around an eye, since some patterns require eye-pressure screening for glaucoma and evaluation for the uncommon Sturge-Weber syndrome. Most facial port-wine birthmarks are not associated with this syndrome. CHOP guidance

Seek urgent care if there are seizures, developmental regression, vision changes, a painful/swollen eye, or rapid change in the patch.