Yes, as a probably elderly person, I agree with these comments. There is plenty of information out there re making communications of any kind, including websites, clear and legible. And yes, it should be possible for the user to control the text size, making it larger if necessary. Your research might be helped by talking to relevant groups such as Help the Aged, RNIB etc. From September 2020, Web Accessibility Regulations build on existing obligations for public sector websites and apps to be accessible, the RNIB has a factsheet on this which might be useful.