If the six days are symbolic, then Exodus 20v11 would make no sense. For in six days the LORD made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy.
At the end of each day in the creation account it says there was morning and evening. God tells us in plain language, simple and uncomplicated.
Morning and evening simply mean the end of one phase/era and the beginning of another time period. The length of a 'day' can be anything from a few hours or until the end of an age.
H3117
יוֹם
yôm
yome
From an unused root meaning to be hot; a day (as the warm hours), whether literally (from sunrise to sunset, or from one sunset to the next), or figuratively (a space of time defined by an associated term), (often used adverbially): - age, + always, + chronicles, continually (-ance), daily, ([birth-], each, to) day, (now a, two) days (agone), + elder, X end, + evening, + (for) ever (-lasting, -more), X full, life, as (so) long as (. . . live), (even) now, + old, + outlived, + perpetually, presently, + remaineth, X required, season, X since, space, then, (process of) time, + as at other times, + in trouble, weather, (as) when, (a, the, within a) while (that), X whole (+ age), (full) year (-ly), + younger.
Total KJV occurrences: 2295