Small yellow spots on tomato plant
I just bought some gardener's delight tomato plants last week. They were in very small pots and tended to top over. So I replanted them in multipurpose compost in slightly bigger pots. They are in my porch where it's bright and sunny. Unfortunately, two of these plant's leaves have yellow spots and a couple of leaves are already yellow. I do turn these around daily.
If the spotting is affecting only a couple of leaves, remove those leaves as well as the yellow ones - it's nothing to worry about. If many more leaves become infected, however, you might have one of several fungal or bacterial infections that trouble tomatoes. You can take samples to the Extension Service for analysis; this link will help you locate one: https://www.gardeningknowhow.com/extension-search/
However, since you bought the plants only a few days ago, I think I would return them and ask for a refund. It would appear that they were infected when you bought them.