Currently, I am a Podcaster, I usually use Canva to create podcast cover art.
Are you planning to add the Podcast cover to Baseline?
The designs in Baseline are both brand-synchronized and beautiful. I love using Baseline to create designs for my blogs and social networks because it saves me a lot of time.
If you can update Podcast covers in the future, that would be great for Podcaster. 
Hi @kieumanh2211 and welcome to the community,
We can definitely add some podcast cover templates. Is there a standard size used for Podcast covers? If you have a link to the requirements that would be awesome!
Apple likes the show cover to be 3000 x 3000 pixels, but can accept anything from 1400 x 1400 (which used to be the standard)
Info here: Artwork requirements - Apple Podcasts for Creators
Your response @websam is very complete. You can refer requirements for the standard Apple Podcast in here. 