What you want is what Canon offers with their RAW files: RAW (full size RAW), mRAW (medium size RAW), and sRAW (small size RAW). On Canon’s 18mp sensors, that equates to 10.1mp for mRAW, and 4.5mp for sRAW. Since Canon introduced this feature, I’ve found it to be tremendously useful. I shoot weddings, and with the huge volume of images that we shoot, larger file sizes quickly add up. I’ve always found that 10mp is plenty for most wedding images, so I shoot most of the wedding at mRAW. I only switch to full resolution RAW for the portrait and large group shots.
I love being able to adjust the resolution of my RAW files, just like you can with JPEGs. Hopefully, other manufacturers will adapt this strategy with their RAW files too.
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.