The answer to this question depends on the intended purpose of your artwork. In order to find out the recommended color profile, ask yourself the following question:
“Where will my design be used?”
Will it be for both online sharing and printing?
Or will it be only for printing?
Answering that question can solve a lot of headaches down the line and save you from endless color tweaking, trouble-shooting, and products that are disappointing in real life.
Designing for online sharing & printing?
For example: You’re a digital artist and publish your artworks online (e.g. Instagram), but also want to use them for printing on products.
In this case, design in RGB for online sharing and convert a copy of your work to CMYK to use specifically for printing purposes.
Converting your color mode can be done in your designing app. This gives you a good idea of how your colors will change, and how they will look on your printed product.
Please note: Switching between the two modes should flatten more vibrant/ saturated RGB colors that are not possible to duplicate with the CMYK model.
While we can never be 100% accurate, it is still a good way to check how RGB colors translate into CMYK colors, aka how colors you see on your screen translate into colors on your product.
Designing only for printing purposes?
For example: You want to sell t-shirts and mugs with funny slogans and/or illustrations.
Then minimize tweaking headaches by designing in CMYK from the very start.
Designing in the CMYK mode means that you are only using colors within the CMYK range. This minimizes discrepancies between what you see on your screen and what you get on your printed product.