I hope you are well today and thank you for your question.
Do I have to use mailchimp to match the design provided?
No
Is there a free email plugin you recommend where I can use Gmail free SMTP for simple contact emails.
The mailchimp is optional so if you don’t integrate it with the contact form then the email will be sent on the email that you have configured in the contact form settings.
If I swap out mailchimp, will i need to change anything on the contact form such as the shortcodes below: