Import your render into photoshop

select: subject

Select: modify: smooth (to taste, but not too much. It'll smooth out your eventual stroke some)

Select: modify: expand (to taste, to counter the smoothing)

Edit: stroke

...there's your outline.

---

W10 Pro, HP Envy X360 Laptop, Intel Core i7-10510U, NVIDIA GeForce MX250, Intel UHD, 16 GB DDR4-2400 SDRAM, 1 TB PCIe NVMe M.2 SSD

Mudbox 2022, Adobe PS CC, Poser Pro 11.3, Blender 2.9, Wings3D 2.2.5

My Freestuff and Gallery at ShareCG