Please note we have two ц's in Ukrainian - the 'normal' one and the palatalized one. You can read about palatalization in Ukrainian here.
ц in офіціант is the palatalized one. It's exactly the same as ц in "ця", but not the same as ц in "цей", which is just your normal non-palatalized ц.
Palatalization doesn't depend on the position in the word - it can occur at the beginning, in the middle, at the end of a word. In spelling it depends on the next letter.