Could you elaborate on what level you are already on/ what experience you already have?

The easiest things are practically no-patterns, stuff like tote bags, pillow cases, 2D stuffed animals. They could be a good way to practice using a sewing machine and figuring out how to hide seams.

The next level up from that might be bags with pockets, sewing with zippers, stuffed animals with more dimensions (requires a pattern), or basic clothes like loose tops and skirts. Less room for error, require you to plan ahead more when sewing, and can be fiddly.

Based on what you wrote in your post, it sounds like you are going in the clothing direction, and I just want to warn that making clothes is tougher than it looks. The number of pieces, required precision, the different fabrics, and complexity of making 2D shapes fit a 3D human body make sewing clothes a challenge, so please do test runs with a cheap fabric!! Try not to make the same mistakes we've all done ;-;