Since the new user account looks normal on the same laptop, I’d focus on something in the original Windows profile rather than the display or resolution.
First check Settings > Accessibility > Text size and make sure the slider is at the default. Then check Settings > System > Display > Scale and confirm it is using the Recommended value.
If those are already the same, check the browser itself. For Edge/Chrome, press Ctrl + 0 to reset the page zoom to 100%.
If only the browser tabs and menus are still larger in your main account, I’d try resetting the browser settings/profile next. Since the second Windows account is normal, that would be a good way to narrow it down without changing system-wide display settings.