What is the difference in usage between 似乎 and 宛如?
似乎(as if; seem like) is more modern and colloquial, 宛如(just like; as if) is very classical and literary

似乎 mainly refer to metaphorical resemblance, 宛如 mainly refers to physical resemblance

Example:

似乎要打仗了 (seem like we will go to war)

似乎忘了自己是誰 (seem like/ as if forgotten who he is)

五座山峰一列排開，宛如五指，故名五指山 (the five mountain peaks stand side by side, just like five fingers in human hand, hence the name 'Five Fingers Mountains'

看他面目猙獰，宛如惡鬼猛獸 (look at his ferocious face, just like a demon or a beast)

The modern/colloquial equivalent of '宛如' is '就像'