Suppose I buy one filament connector. I want to know if we can connect PLA filament with PETG filament or ABS filament and TPU filament. Make different 3D printer filaments into one filament. Then we can print different 3D printer filaments into one model with a normal 3D printer.
No, connecting different types of filament will not work.
At the most you could do the different type within the material eg. PLA Basic/PLA Matte/PLA Silk/PLA-CF, could be interesting for someone creative. But as JonRaymond said generally different Materials won’t be successful even if you could match the temperature change just at the material switched.
PLA/PETG don’t stick together well - one is sometimes used as support for the other just because they do not adhere to each other
Temperature requirements usually vary too much between different materials. ABS needs high bed/nozzle/chamber temperatures and a closed chamber, TPU needs lower temperatures and a cool, open chamber. Plan for lots of failed prints and clogged nozzles.
You can join different colors of the same materials, perhaps to use up small amounts of filament at the end of a spool, but there is no practical way to predict where the change will happen on the model, so appearance cannot be a concern.