If the employer does not allow for a note in the application process, how do I reflect my scheduling requirement?
If these are your requirements, you are looking to work part-time. (In most industries, at least in the US, employers consider anything 30-32 hours per week or less to be part-time).
Instead of applying for a full-time position and adding notes, apply only for part-time positions.Instead of applying for a full-time position and adding notes, apply only for part-time positions. (Or look for ads for positions that have the number of days and the total number of hours explicitly specified, and that meet your requirements.)
That way, you'll get interviews for jobs that might actually meet your requirements, you won't be misleading anyone, and neither your time nor the hiring manager's time would be wasted.
I plan to apply to full and part time positions. Since I am in a professional role, majority of positions are full time.
In my opinion, this is a mistake, and risks wasting everyone's time.
You would be far better off seeking the minority of part-time positions in your field, rather than expecting folks offering full-time positions to change their requirements for you.