Not usually.
No they are not because adjacent angles are on the same side while vertical angles are on the opposite therefore vertical angles are non adjacent.
They are referred to "adjacent angles"
adjacent angles
Adjacent angles are angles that have the same vertex (corner) and share a common side.
A polygon that all sides and angles are the same measurement is a regular polygon.
That means they have the same measurement. Any two angles that have the same measurement (for example, in degrees) are said to be congruent.
Adjacent angles.
Two angles are adjacent if they have the same vertex, share a side and do not overlap. It is, therefore, perfectly possible for two obtuse angles to be adjacent. In fact, every pair of adjacent angles in a hexagonal tessellation (a honeycomb, for example), consists of a pair of obtuse angles (120 degrees).
adjacent
Adjacent angles are two angles that share a common vertex and a side but do not overlap. Congruent angles are angles that have the same measure, meaning they are equal in size. If two adjacent angles are congruent, they each measure the same, making them both equal in degree. This often occurs in situations involving geometric figures, such as when two angles form a straight line or a right angle.
Adjacent angles.
Same-side interior angles are supplementary. They are not always congruent, but in a regular polygon adjacent angles are congruent.