you could use xeev or m3u4u.com , they both have their own epgs and logos (xeev is paid, m3u4u is free)
Logopedia is a great resource and constantly updated. You should be able to pull direct links to the .png files for your EPG/Playlist editor - https://logos.fandom.com/wiki/Logopedia
I also found this repository awhile ago that's a little more rudimentary but has thousands of logos - https://github.com/Tapiosinn/tv-logos
Logopedia.
https://logos.fandom.com/wiki/Logopedia
Most are already in PNG with transparent backgrounds.
For example https://logos.fandom.com/wiki/HBO
And
https://logos.fandom.com/wiki/Telemundo
Ita also neat because you'll be able to find older versions of logos too.
I plan on changing ALL the channels to ancient logos on April Fools Day for my wife
Google the channel.... Download the image you like.. Upload the logo url
Iptveditor
This is my collection should just about cover it but depends on the size needed as most of these are 270x83
https://drive.google.com/drive/folders/1i9a4tVyuqAYi9Bj-Bxauj1Q72GIbUdFG?usp=sharing
Your provider should give one to you
If you know how to input them into whatever you are using then Wikipedia would be best as they are usually PNG files which are great quality and small sizes.