Here I am sharing the small procedure about how to use own custom font without the help of plugins in wordpress site. This procedure can be used for any type of sites or platform.
Here are the steps:
- At first upload your choiceable font ( which you want to use in the site ) in the root directory using ftp or through cpanel. I have attached screenshot for better understanding

2) Put the css below in your style.css or custom css portion ( please change the url in the code as per your site url)
@font-face {
font-family: "myfont";
font-display: Swap;
font-weight: Normal;
font-style: Normal;
src: url("https://yoursiteurl.com/myfont.ttf");
}
3) so you are done, but to use the font using css, you need to use css similar to this
article, article * ,.entry-content,.entry-content *{
font-family: "myfont";
}
Feel free to let me know if you have any question regarding this.