Hi, what model of the printer do you have?
You can increase font size with POS commands. In Elementary POS APP go to Menu:
Settings->Printer settings->Show advanced setting:
To the field "Before print" try to add these ESC codes: 1D;21;11
It should double font size.
Instead of increasing font size, you can use receipt template and emphasize important fields.
In Elementary POS Office:
Menu->Company settings->Modify custom receipt.
You can define your receipt layout there. Use[large]
to make the row bigger.