Identify the sound device used in sonnet 73 and state which sound device and in what lines?

So sound device used predominantly throughout Sonnet 73 is Rhyme.

Sound devices are literary tools that writers use in prose and poetry to colour and add flavour to prose or a poem. It helps convey and reinforce meaning and makes the writ vibrant, emotive and pleasing using sound. There are several sound devices. Some of the most frequently used are rhyme, alliteration, repitition, and assonance

A rhyme is said to have been used when in prose, poem or song, the author uses like sounding words at the end of each sentence or each line. For example:

She loves to dance

He loves her stance

Notice how each word ends with a similar-sounding word dance and stance.

Explanation:

In the Sonnet 73, It's easy to see that lines 1 and 3 each  end with the same rhyme (behold, cold)

Lines 2 and 4 also share a rhyme (hang, sang)

Lines 5 and 7 (day, away)

Lines 6 and 8 (west, rest)

Lines 9 and 11 (fire, expire)

Lines 10 and 12 (lie, by)

Lastly, lines 13 and 14 (strong, long).

Cheers!

beowulf sets out on his journey for daneland. -- 1

hrothgar welcomes beowulf. -- 2

beowulf waits for grendel to attack heorot. -- 3

beowulf succeeds in defeating grendel by tearing off his arm. -- 4

beowulf fights with grendel’s mother. -- 5

beowulf sets out for his fight with the dragon. -- 6

beowulf sets out for his geatish homeland. -- 7