Does ideas have an apostrophe

Idea is a singular noun, meaning one idea.

Ideas is a plural noun, meaning more than one idea.

You would not use an apostrophe on the Word idea, except in some circumstances. For example, you could write The idea's beauty is... for the singular possessive. But it would typically be rare to see idea become a possessive. You'd more likely see idea joined with a name that needs an apostrophe, such as: John's idea was so good, the council used it.