You may find something in the Registry of Deeds records in PRONI. The records are summaries of the original document, known as memorials. They are indexed under the name of the person making the transaction and also under the townland involved, but not under the name of the person acquiring the property. So a transfer from Smith to Brown is indexed under Smith but not Brown. And whether an index entry refers to a Smith you are interested in is not always obvious until you have got the copy of the document out. The records and their indexes are kept in 5 year batches, so if you don’t have an exact date, you may have to go through quite a lot of indexes to do a comprehensive search.
The majority of people in Ireland in the 1700s leased rather than owned. 10% of the population owned 90% of the land, something that was a major grievance.Many longer term leases, especially those for 3 lives, were registered in the Registry of Deeds and can be a treasure trove for a genealogist as they name the 3 generations, mention any widows with a life interest and name the lands involved, and often people’s previous addresses. So can be complex and time consuming but helpful to search Registry of Deeds records.
The records are on microfilm and are not on line and so you’d need to get someone to go through them in PRONI for you.