What is the best alternative to Manikin on iPhone?

Magic Poser - Art Pose Tool, A tier, #2 in pose reference.

Is there a free alternative to Manikin?

Yes: Magic Poser - Art Pose Tool (A tier, #2) is free to download, with in-app purchases.

No. Manikin is #1 in pose reference.

Manikin is S tier, #1 of the 6 tiered apps in pose reference. Here is everything that competes with it on iPhone, in tier order.

2
Magic Poser - Art Pose ToolA
Free + IAP · ★ 3.8 · 16,969 ratings · score 86
Mobile 3D posing app for building character poses, scenes and lighting as drawing reference.
3
Photogenik: Pose & Photo CoachC
Free + IAP · ★ 4.6 · 201 ratings · score 64
Free iOS app offering posing ideas, spoken photography guidance, a pose library, photo selection help, and a photo.
4
SnapPose: AI Photo Pose IdeasC
Free + IAP · ★ 5.0 · 1 ratings · score 60
Finds real pose references matched to a photo, text description, or landmark, with a live pose outline camera.
5
Easy Pose -Best Posing AppD
Free + IAP · ★ 4.0 · 1,117 ratings · score 57
Free app for drawing that poses adjustable human body models, with joint controls, up to 6 models, and PNG export.
6
posing - pose camera guidesF
Free download · ★ n/a · 0 ratings · score 25
Pose-reference camera that turns photos into stick-figure guides and saves your captures to a private gallery.

What is the best alternative to Manikin on iPhone?: Magic Poser - Art Pose Tool, A tier, #2 in pose reference.
Is there a free alternative to Manikin?: Yes: Magic Poser - Art Pose Tool (A tier, #2) is free to download, with in-app purchases.
Does anything rank above Manikin?: No. Manikin is #1 in pose reference.