Hey thanks for the question, as far as I've tested as long as you bring the assets into the engine you can scale the assets in there and they should scale properly. Try scaling in .5 intervals so 0.5, 1.0, 1.5 etc. I think that would give the best results. It could also vary depending on which engine you're using. The textures are baked into the models uv's so they should just scale along with the model (although making the models too big may result in blurry textures)
Hope this helps and answers your question