My recommendation is to always be careful with 3D models and textures.
Lots of beginners on Blender (or any modelling software) doesn't know about optimization and end up making unnecessary high poly models. Search for lessons about optimization and try to make models as low poly as possible.
Textures can be really heavy depending on the resolution. Try to use textures with the lowest resolution possible (pixel-art games can look good and run well at the same time). You can always downscale textures with any image editing software (even Paint can do it). My general recommendation is to not use textures with resolution above 512x512 but that's not a rule.
These two factors alone make lots of cheap indie games run very poorly. Sometimes "asset flip" games just grab whatever assets they find on the internet and doesn't care about optimization.