Simply, As always there’s no perfect waveform so that’s also there’s no numerology.
For example, If we’re talking about a more narrow subcarrier spacing, we have the advantage of better channel equalization and this will reduce complexity, So when symbol duration is longer is like you’re speaking very slow and it’s easier to understand.
On the other side, In the case of the wider subcarrier spacing, you’ll gain latency advantage.
So 5G offers great flexibility in the radio interface aspects.
For more details about 5G 3GPP NR Frame Structure, please visit this link.