There is no point in that. You will just be getting a strangely modified composite signal. I'm going to use the word garbage and I'm not trying to be a snob, it's just the saying. But you will be getting "garbage in garbage out". Converting from composite to scart will do very little. Your composite input will essentially be the output. Not that composite is bad, it just won't change much. And depending on the equipment, could be worse.
Composite cables basically have 3 channels. Video, audio left, audio right. Scart is a general standard. What I mean by that is the cable is standard, but you can have all kinds of video. The cable has 20 pins (channels) that support several video modes. SCART is not necessarily better. This is because there is RGB SCART and composite SCART. RGB SCART is better. But not composite scart is the same as composite. Refer to the diagram below.
A composite to SCART converter will remain three channels. It will use pins 1,3, and 19. This will provide no difference in quality. It is simply a pass through with a different cable.
RGB scart uses a lot more pins/channels for higher fidelity. It will use several of the RGB channels for video plus channels for sync and audio. It's essentially a jump in quality due to the separation of channels. The jump in quality from RF to composite is due to separating the audio from video. This is similar in the jump from composite to RGB.
Now the composite to RGB converters do not separate the mashed up video on one channel to several channels. This is really hard to do. So, composite to RGB is still composite.
You might gain a jump in quality due to the HDMI conversion. But this is entirely due to the upscaler. Most are crap. Some are good. But expensive. Really expensive.
TLDR: Get a scart cable. More specifically, get an RGB SCART cable.
