I think what you mean to ask is, must the seller pay their agent an additional commission, for acting as a dual agent? The other folks are correct in that the buyer doesn't directly pay a commission, but they indirectly will through the sale.
I don't know about Texas, but in California, we bought our house, there was a customary 3% commission to the seller's agent, and 3% to the buyer's. I approached the seller's agent as representing myself. The agent eagerly wanted to represent both parties, but I said no. The offer I submitted showed 3% to the seller's agent, and 0% to the buyer's agent. That represented $12k more to the seller, and it may have induced them to accept our offer over others that had a slightly higher sales price. I arranged for inspections, disclosures, escrow with a title company, and a loan. Not hard, anyone who has managed small projects could do it. If you were an agent in the past, hopefully you remember the things that need to happen.
Texas law may vary. Here, a person may act as their own agent, in buying a house for themselves, but not for others.