GIMP is a free program for such photo retouching, image composition and image authoring. Essentially it's the closest thing to Photoshop you can get for free.
Suggest and vote on features
GIMP Features
Support for LayersGIMP supports the organization of elements through a hierarchical order that can be manipulated/viewed independently.
DRM FreeNo Digital rights management (DRM), i.e. no copy protection.
Ad-freeGIMP doesn't contain any form of external advertising.
PortableGIMP can be used from a USB stick or similar with no prior installation.
Dark ModeGIMP supports dark mode for comfortable usage in low light conditions.
Works OfflineGIMP can be used without the need to connect to the internet.
Non Destructive EditingGIMP can make changes to a file without overwriting the original data, which remains available in case you want to revert to it.
Custom BrushesYou can use modified/custom brushes in GIMP.
