Development at Shop Rear
Recommend taking what the agent tells you as "sales puff". The agents objective is to sell the property for the vendor to collect the highest commission as quickly as possible. To do this some agents may stretch the truth with regards to what can & can not be done to a site.
Keep in mind that with regards to "sales puff" almost anything is possible with enough $$$ & time. Thats one of the functions of the Land & Environment Court; to test whats permissible.
Unless you have deep pockets, recommend focusing on what's permissible.
Many commercial sites do not allow mixed use (i.e. commercial + residential) or multi lots (strata or Torrens). Not sure what you have in mind here.
You need to check the properties zoning & have a look at the local authority's (Councils) DCP & LEP to see whats permissible.
While it may be possible to create small lots on an existing site, its very important to work out what the market needs (demand), what other alternatives are (supply), how much it will cost to the supply the product & what the return will be.
Some creatives have created strata lots of 1-2m2 for ATM machines then sold them as a going concern / investment. I've seen cigar & wine storage strata lots proposed which are even smaller.
Bottom line is to do you own research. And as previously pointed out it's best to keep specific sites you are interested in purchasing to yourself while you do your due diligence.