If you have a vintage style engagement ring, you’ll want a wedding ring that’s a close match design-wise. It’s ok to mix vintage eras, as long as they are quite close to each other.
For example, an 1920s Art Deco engagement ring will look great with a 1930s diamond eternity-style wedding band.
But an elaborate 20th century antique wedding ring with filigree work would not go that well with a geometric 60’s retro engagement ring.