Check with your domain registrar. In most of the cases, your domain registrar will be managing the DNS settings for you - unless you are using your own DNS provider or a solution like Cloudflare.

You can go through one of my earlier posts (link below) on integrating with GSuite email if you face issues while setting it up:

https://www.odoo.com/forum/help-1/question/customers-cannot-send-email-to-my-company-address-info-medinfo-com-151107#answer-151129