Hi Ramesh,
For the individual report field under font size, you can try something like below:
if len(<database field>) > 10 then 9 else 10
Here you need to replace the <database field> with your actual database field.
>10 signifis your databse field length greater than 10, then font size will be set to 9.
If databse field length is less than 10 characters, then it will be set to font size 10.
You can adjust the values as required.
Hope this helps you.
Thanks,
Raghavendra