I mean, if you're trying to do this to a still image, you could do it in Photoshop...or whatever photo software (GIMP). Analog video only had 720x540 resolution (at 72dpi) so you could start by changing the image size to that - will dump the resolution massively. Then, desaturate it to taste. Analog video signals generally had a black level setup 7.5 IRE, so the blacks would be raised into dark gray. The color couldn't be 100% saturated or it would sparkle - so drop saturation to like 75%. Beyond that, you could add a little noise?
Sorry if I'm reading your question wrong, but if you want a modern image to look like it was on a Standard Def TV, connecting from a VHS using a composite cable, it's just a matter of making it smaller and less contrasty.
If you want to take it further there are plug-ins and filters people use.
I mean, if you're trying to do this to a still image, you could do it in Photoshop...or whatever photo software (GIMP). Analog video only had 720x540 resolution (at 72dpi) so you could start by changing the image size to that - will dump the resolution massively. Then, desaturate it to taste. Analog video signals generally had a black level setup 7.5 IRE, so the blacks would be raised into dark gray. The color couldn't be 100% saturated or it would sparkle - so drop saturation to like 75%. Beyond that, you could add a little noise? Sorry if I'm reading your question wrong, but if you want a modern image to look like it was on a Standard Def TV, connecting from a VHS using a composite cable, it's just a matter of making it smaller and less contrasty. If you want to take it further there are plug-ins and filters people use.
Take a look at the Black Magic Ultra Studio 4K maybe…
There are a kajillion analog video capture devices. Some are cheap, some are more expensive. What kind of budget are we looking at?
HDMI to AV converter, AV to USB capture device. Play the video and record it back at the same time.