Thumbnail template needed for YouTube channels

I am looking for a designer who can share Thumbnail templates that can be used for our YouTube channels. I am looking for 50 different templates
In case you are interested, please share the estimated cost and timelines for the same along with a sample set of 3 design templates which will be used to shortlist
For example, most of the channels below are following a standard template while we keep changing the content within the template as per the content. Looking for additional design options which can be used.
https://www.youtube.com/c/UnacademyCAFoundationPro/videos
https://www.youtube.com/c/UnacademyClass11and12/videos
https://www.youtube.com/c/economicsonyourtips/videos
https://www.youtube.com/channel/UC8oozlFrNYYprZlYLmdRtgg/videos
https://www.youtube.com/c/UnacademyClass9and10/videos
https://www.youtube.com/c/Kreatryx/videos
https://www.youtube.com/c/UnacademyGATECECH/videos
https://www.youtube.com/c/UnacademyGATE/videos