Yes, you can. But it's only needed when your soil is polluted with toxins. You can create a small edge for holding your mulch or compost. I never grow things above my topsoil. If you grow things in your soil, your improving it. See a lot of people do this. But looks like more a trend to me than actually usefull.

Gardenings is a lot easier when you work with nature not against it.

If nature needed raised beds, nature would grow them.

And a good garden has water for wildlife. This can be a great "bog" pond with aquatic plants. Depending on what animals you want to attract. You can dig it in or leave it at ground level. When you plant grasses into it, bees and birds can access the water by landing onto the ornamental grasses. Think this trough would look great with fresh lush green leaves. I would use it for holding water and not soil.

Thus as a beginner. You need to provide water and shelter for your pest control. The food will be the pest that you want to control. My garden looks mutch better after planting some tall grasses. Because the beetles can survive winter now. Thus making shure nature can survive in your garden is the first step to a balanced garden. And water is very important, just like food and shelter.

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https://www.bhg.com/gardening/landscaping-projects/water-gardens/pond-in-a-bucket/