I have got some new features you could add to Shotcut first as you can put colour solid and. Change the colour of it in shotcut.
Already a feature to add a color clip.
And change the color.
Open Other → Color
Click on Color, or click OK to leave as a transparent color clip.
Ability to change the color of the clip at any time.

I didn’t know that thank you for telling me. That really means a lot.
I got a question did watch YouTubers who have progress bar in they video by them. Because if you have that why I asked for the features so I can do it for my video again thxs.
Transform = Size, Position & Rotate video filter in Shotcut