Q.How Far Apart Should Vegetables Be Planted So They Don’t Affect Each Other (ie. Tomatoes & Cabbage)?
I read that certain vegetables can have adverse effects on each other, namely tomatoes do not like cabbage or pole beans near them or sweet peppers and hot peppers will cross pollinate and make the flavors go off. Looking to find out what a safe distance apart would be since I’m working with a small garden.

Certified GKH Gardening Expert
Whether you buy seedlings or start from seed, the tag or envelope should tell you the mature height and width. Use that width to determine how far apart you should plant your veggies. The article below also includes how much space to include.
To save space, you can grow most veggies in large containers. You also can use hanging baskets and grow more veggies vertically.
Here is more:
https://www.gardeningknowhow.com/special/urban/gardens-in-small-spaces.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-plant-companions.htm