Does wearing glasses during a speech make you look smarter? Do I look smarter to you now? No. I'm just a guy who's wearing glasses.
I think it's a huge myth out there that somehow you look smarter, more intelligent wearing glasses. Here's the bigger problem.
Focus on saying something interesting to people. Not on gimmicks like wearing glasses if you don't need glasses. Glasses in and of themselves don't do anything to help your credibility.
And in fact certain glasses can cast shadows on your eyes. And if your audience can't see your eyes it's just another barrier between you and your audience.
Now, if you do wear glasses that's fine. Some great speakers wear glasses. I'm not suggesting you get rid of glasses. But I am troubled by this idea of giving all this thought and energy and going buying glasses before you've actually figured out, "Do I know I have something interesting and compelling for my audience? Have I given them great examples? Great stories. Great case studies."
That should be your focus. Not props and theatrics like fake glasses you don't need.