Service tax applicability

Generally yes,
With the introduction of GST , there was certain loopholes under service tax act.
Sales of Goods Act is a seoerate Act and Goods and Service Tax Act is different.
Those were two seperate legislations .
As a result of the fact, Goods and Service Tax Act was introduced.
There sre several other enactments.

GST at 18% is applicable to all taxable value of supply provided by an agent, including the sale/purchase of advertising space/time. Following are some of the services provided for a fee/commission or on a contract: 

Sale of land/building.

Any retail/wholesale trade service.

Property management service.

Real estate appraisal service.

Commission agent services to negotiate wholesale commercial transactions.

Usually, a supplier of goods/services is required to pay GST. But, in some cases, a recipient of goods/services is required to pay GST called a reverse charge mechanism RCM

GST AT 18%
IS APPLICABLE FOR ALL TAXABLE PERSON FOR TAXABLE VALUE OF SUPPLY PROVIDED BY AN AGENT .
BUT THERE IS A THRESHOLD LIMIT.