So I found the setting you were looking for, and I must have misunderstood the issue. I thought you were having troubles climbing the slope, and not the visible collision.
All you need to do is open your characters blueprint and uncheck the option ‘Use Flat Base for Floor Checks’. This will allow the character to stand closer to the platform. This option is found within the Character Movement component within the dropdown for Walking.
Use Flat Base for Floor Checks
Let me know if you have further questions.
Thanks,