Hello Karen,
As Elise posted, 100% is the minimum text size that cane be set.
As a workaround, you could do the following to reduce the size of everything that would also include text size.
1) Increase display resolution if able.
https://www.tenforums.com/tutorials/4910-change-screen-resolution-display-windows-10-a.html
2) Decrease DPI scaling level of display if able.
https://www.tenforums.com/tutorials/5990-change-dpi-scaling-level-displays-windows-10-a.html