Yes, you can use Google Fonts and be GDPR compliant. The only time Google Fonts breaches the GDPR terms is when served via their content delivery network and no permission to send Google your website visitors' IP addresses has been received. If you can severe the need for your visitor to expose their IP address to Google, you can keep using Google Fonts on your website. To severe the connection between Google and your visitor, you can either locally host Google Fonts on your own website or revert to using WordPress’ system default fonts