When a business location goes from one sort of business to another, who is responsible for making any changes to the facilities, the incoming business owner or the building owner? Let's say that the old outgoing business was a hair salon in a mall. So the space currently has the kind of sinks and things that you would use for washing hair. The incoming business is a bakery, and needs ovens and and other commercial kitchen facilities. Does the bakery foot the bill for ripping out the hair-washing sinks and installing the things they need, or the mall owner? Does the answer change if it is a chain bakery like Cinnabon, vs a purely local bakery?
What you are referring to is called "Fitout". (Here at least, perhaps it differs around the world!) Usually it is the tenants responsibility, basically they're leasing the building and can use it how they wish. There is often a clause to that says technically they must return it to the original condition if requested at end of lease. In reality, in my experience this rarely occurs. For example, we just painted the front door of our office blue - it was brown - technically we could be required to paint it brown again if we move out. In reality, it looks nicer blue (plus the brown was horribly faded) and the landlord is unlikely to care - they'll just leave it and let the next tenant repaint if they want to, and again at the tenant's own cost. Likewise, any other changes we made we could be required to undo/change, but in most cases they'd just leave it and let the next person sort it out.
Sometimes they will lease a premise that's already got existing fitout or with some $ towards fitout included. Some building owners might have an arrangement with a particular contractor to do the fitout, or have other ways of working it out. In our case our lease included having some repairs done to the building, and also new carpet and paint. This all had to be done prior to the lease officially commencing and us moving in, so they weren't getting paid until it was done. But now that we're in, if we want other changes we have to sort it out ourselves (unless it's a problem e.g. something stops working that they were responsible for). Obviously each situation varies, but unless contractually agreed the general rule is "as is, where is", you get exactly what you see unless you negotiate something extra.
**Of course, local laws etc may vary and require a landlord to make specific provisions. But this is more general information not legal advice!