You can set the site-wide text font and colour for your website. This will become the default formatting for your text. Remember that the formatting applied in the Text Widget will override the site-wide formatting.
Navigate to Site Settings > Text.
Here you can choose your desired font, colour and size. Note that you can add your own colours to the colour palette by adding a hex code
in this area, as highlighted below, or you can add them as custom colors on the Custom Color tab
Once you have selected your default font, colour and size, click Save.
The colour and font changes will now be implemented site-wide.