What is consonance?

Consonance is a poetic sound device. Most people are familiar with alliteration: the repetition of initial consonant sounds in words that appear in close proximity. Alliteration is a specific type of consonance; consonance is the repetition of consonant sounds in words that are close together.
Consonance is the term commonly used to refer to repeating internal and/or ending consonant sounds in particular. Repeating consonant sounds that don't begin words has a similar but more subtle effect than alliteration. Poets often combine consonance, alliteration, and assonance to produce a pleasing or lyrical quality in their lines of verse. Assonance is the repetition of vowel sounds. One common use of consonance and assonance together is rhyme. Words that end in the same vowel and consonant sounds, such as near and fear or such and much, rhyme.
Edgar Allan Poe's "The Raven" is a very lyrical poem that makes excellent use of poetic sound devices. Consider the opening lines:

Once upon a midnight dreary, while I pondered, weak and weary,
Over many a quaint and curious volume of forgotten lore—


Most readers will recognize the alliteration immediately: the /w/ sounds in the first line ("weak and weary") and the /k/ sounds in the second ("quaint and curious"). However, the repeated /n/ sounds that occur in the middle or at the end of words contribute to the flow of the language and the almost hypnotic mood that the lines evoke.

Consonance, like alliteration, is a sound device that poets can use to great effect in creating memorable and effective verse.
https://literary-devices.com/content/consonance/