Clothing Design

Congrats on starting your journey in clothing design! There are many software options out there, but my favorite for designing clothes is Adobe Illustrator. 

A lot of this comes down to the "why" before the "how." Why do you want to use software for this over pen and paper? Lots of pros still start their designs using analog tools because that's what gets their ideas out most quickly, so it's still totally valid to sketch your ideas that way if it works well for you. However, if you want to create slick, polished designs to present in a professional context, you could absolutely use Illustrator or Photoshop to draw them out. The links above would definitely give you options to explore.

As an in-between, what about drawing on a tablet using Adobe Sketch or Adobe Draw? Those are more limited versions of Photoshop and Illustrator that focus entirely on the most intuitive sketching tools, and that plus an iPad or similar mobile device makes for a great digital sketchbook. You won't be able to create 3D models on either of these, though, but since fashion illustration is commonly 2D anyway you'd still have a professional presentation.

You will certainly want Illustrator or similar for lots of things

Eg, see Sew Heidi channel on Youtube

Sew Heidi - YouTube

But  for creating patterns, and grading you may want a more specialist software

but all are very expensive, made by  Gerber, Lectra, and Optitex etc

You could try free open source

Valentina

Vdeo tutorials available , eg

Tutorial: Pattern Drafting with Valentina - YouTube

Curious Labs "Poser" 3D figure and design software might still be available.  "Digital Art Zone" plug-ins of pre-built models ( i.e., Michael and Victoria ) along with a "Motions" CD ( per Pubperfect.com ).  Illustrator may be a solution for creating patterns, but not sure how that would morph into 3D 360 approaches. 

Illustrator. Charactor animator as well