As a freelancer, you could probably make an average of 30-40 USD per hour, but very experienced designers could go up to 80 USD per hour (10+ years of experience).
Working for larger companies, but in smaller teams, has seemed to work out better for me. I'll give you real life numbers to work with; by the time I had ten years of experience, I was making $80,000 USD a year (inclusive of bonuses), Where I'm currently working, it's closer to $90,000 (inclusive of bonuses).
Much of this was how flexible I made myself within my environment. Rarely was I just designing PowerPoints, identity systems, or making landing pages. In one team, I was embedded with industrial designers, and had the opportunity to handle CMF (colours, materials, and finishes). Currently, I have pivoted to editing video and audio, but branding is still one of my chief duties.
How broad your skillset is can lead directly to projects and salary ranges you didn't think possible.
I cannot imagine paying a graphic designer in software (who would probably more likely be called an "interface" or "ui" designer) as little as $45k, even to start. I wouldn't be surprised to double that. I know that graphic designers who work in marketing, advertising, and other fields make much less though.