The advanced strategies for favicon design and optimization in Seo are as follows:-

File Format:- Favicon can be used in different formats, but the most widely supported or used formats are .ico used for desktop browsers, and .png for modern browsers and mobile devices.
Size:- The best-recommended size for a favicon is 16*16 pixels for older version browsers and 32*32 pixels for modern version browsers. Some platforms also support larger sizes of pixels such as 48*48 or 64*64.
Design:- Favicons are small in size, they should be simple and easily recognizable. As often, a company's logo or a simplified version of it works well as a favicon.
Tools to Use:- You can create a favicon with the help of many software tools like Adobe Photoshop, GIMP, or online tools like Favicon.io or RealFaviconGenerator.
Examples of Well-Designed Favicons:- Google:- Let's take an example of a Google favicon icon. Simple "G" in shades of blue and red. Take another example of Facebook. White "f" on a blue background. Take another example of Apple. Minimalistic white Apple logo on black.

Steps to create a favicon for your Website:- First of all you have to open image editing software or an online favicon generator tool. After that, you have to create a new 16*16 or 32*32px image file. Thereafter design your simple and recognizable favicon icon and save it as a .ico or .png file then upload or link the favicon to your website.
Difference between Icon and Favicon:- Icons are used to represent the applications, files, or concepts in a user interface, while favicons specifically represent websites in browser tabs and bookmarks. Favicons are small in size, so they don't have enough space for visuals and words used in most logos and used to communicate brand identity.
Sizes are needed for a Favicon on each browser:- 16px:- It is used for general use in all browsers. 24px:- It is used for pinned sites in Internet Explorer 9. 48px:- It is used for firefox in Windows 8 and Android. 72px:- It is used for iPad home screen icons. 96px:- It is used for the Google TV platform. 128px:- It is used for Chrome Web Store. 195px:- It is used for Opera Speed Dial.
Add a Favicon to Your WordPress Website:- Go to your Wordpress dashboard, and then go to Appearance -> Customize->Site Identity->Select your Icon.

Define Advanced Strategies for Favicon Design and Optimization.