Need Help Finding CSS Coding For Adaptable Font Sizes For All Monitor Sizes

sbphotographystudio

Hello Everyone!
Does anyone know a CSS code that can adapt font size depending on the monitor size? The reason why is because I have a 4K monitor and I need my webpage to be viewed pleasantly while still adapting to the size of a mobile screen. Any help would be greatly appreciated. Thank you.

Here's my website: www.sbphotographystudio.com