This topic is kinda vague, perhaps update the topic with what you need help with… what’s your current progress… what do you want to improve on? etc.
For detail you should use:
Beams, pipes
Add little details (detailed tables, mats, plants etc)
Plugins like 3D text maker
There is truly nothing more you can do other than practice, look at reference images and work hard on even the smallest objects. That is truly how your builds become more detailed.
Building, something detailed or realistic is something you should practice and experiment with doing a quick search around you will find tips and information for creating a restaurant or any build as it’s always good to have a layout created or a image by your side to implement those important details such as textures - detailed scenery and decorations ect.
Always start simple, then as you go on, add in more and more small important details - objects. Always have variety of reference images featuring a specific restaurant you’re wanting use images or look at existing builds for inspiration like the ones your familiar with or wanting to dive in the style or theme. Personally, reference images are a decent method, as these will always act as a guide when creating a detailed restaurant.
Try to find those important details and incorporate them within your build. Take pictures of restaurant around your specific location you could even write down tips and things that help you in a notebook and find ways what makes a restaurant detailed.
Don’t be afraid to try something unconventional in your design. If you have a good idea for a design you like, don’t be afraid to use it and go off of that even if its not something you’d see at a traditional restaurant. When building my restaurant, I knew I wanted it to be unique and something people will go “wow” when they see it. It certainly worked, the restaurant’s gotten pretty good feedback so far.
To summarize, go crazy with your ideas.
Another thing, do not just re-create existing buildings.
It is much nicer if you have a unique design, but if your still new to building and design its perfectly okay to re-create parts of existing buildings for practice, personally I’d avoid recreating if possible in final designs.
That being said that does not mean you can’t be inspired by existing designs, I’d just make sure its heavily customized.