I have recently read a post in where a fellow blogger had to resort to bold font because one of his readers had a difficulty in reading the default text size in grey colour. So, here is how you can increase text size and change text colour in your posts.

Changing text size

You can change text size either all together or one para at a time.

One para at a time

• Once you are on the said paragraph, go to your post settings.

• Under the heading Typography, Select M for medium-sized font (which I would recommend) and L for large. For example:
• This is Medium.
• This is Large.

All together

Once you are done writing your post, press Ctrl + A keys together to select all the content. In Block editor, you will need to keep the Ctrl key pressed while you press A key thrice. Once you see all your content selected, select the text size as explained before.

Changing text colour

1. In the very same way in same post settings, under the heading Color, select Text.
2. Now, select the colour of your choice. I can see various shades of grey, plus white, green, orange and yellow here. (The combinations depend on your selected theme. I can see that mine is quite ugly. 😃)
3. You also have the choice of changing background colour.

As a sort-of-expert in adult education (Instructional Design is about building training courses for adults.), I have found Black print on White/Cream background as the most readable combination.

I am not sure how it works for Classic Editor. I think it should not be that much different, except that you must manually select the text you wish to change. Or maybe the change happens for the entire post.

Let me know how it works for you. Please share with others struggling with text size.