How can I make cool font by my own for copy and paste?

YayText.

A free online cool font maker designed specifically for people who want to stand out on social media platforms that don't support custom fonts (like Instagram, Twitter, Discord, and Facebook).

Unlike traditional graphic design software, YayText doesn't require you to download any files or learn complex tools. Instead, it uses Unicode characters, a universal text encoding standard to convert your normal letters into dozens of stylized variants, including bold serif, cursive script, double-struck, bubble letters, and even upside-down text. You simply type in the input box, and the "cool" versions appear instantly below.

The primary appeal of this free cool font maker tool lies in its speed and extreme ease of use. Once the generated styles appear, you can click any result to automatically copy it to your clipboard, then paste it directly into a bio, tweet, comment, or gaming username.

The tool is completely browser-based for making all kinds of cool fonts, works on both desktop and mobile, and requires no sign-up or payment. Because it relies on standard Unicode characters, the stylized text will be visible to almost anyone on any modern device though it will appear as "plain" text if a platform or device uses a very old font rendering system. It is widely considered one of the most reliable options for quick, copy-paste typography.