Is there a way to change the font in a message box, and make the box larger?
Yes, but it is the main Windows setting that you are changing, and it
will effect all applications.
Right-click on an empty area of the desktop.
Select Properties + Appearance + Advanced.
Select the Message box from the Items drop down.
Select the font and font size.
Save the changes.
I don't know what you mean by "make the box bigger" as the message box
size varies with the amount of text that it has to display.
You might want to consider simply creating your own message form using
an unbound form. This way, only the Access program you are running
will be affected. You would open the form using
DoCmd.OpenForm "FormName", , , , , acDialog