In most corridor cities, yes above 4 feet of height, and engineered design is required with the permit. Walls under 4 feet with nothing pushing from above are commonly exempt in town. On unincorporated county land there is typically no permit, but the physics still apply.
More detail
The 4-foot line comes from the building codes most area cities adopt: retaining walls over 4 feet measured from the bottom of the footing, or walls of any height supporting a surcharge (a slope, a driveway, a structure pushing from above), require a permit and a design sealed by a licensed engineer. Sherman, Denison, McKinney, Anna, Melissa, and the other incorporated cities in the corridor follow this pattern through their permit portals; Durant and the Oklahoma towns run their own equivalents. Under 4 feet with no surcharge, cities commonly treat walls as landscape features and exempt them, though HOAs and lake-community rules (Lake Kiowa's POA, Texoma shoreline oversight) can add their own review. On unincorporated Texas and Oklahoma county land there is generally no residential permit at any height. The important honesty: the permit threshold is not an engineering threshold. A 5-foot wall on unpermitted county land carries exactly the same soil pressure as one in town, and saturated Blackland clay pushes hard enough to rotate an undersized wall regardless of jurisdiction. So the rule here is simple: over 4 feet or under load, the wall gets engineered design wherever it stands, and the written scope names the permit path (or the absence of one) for your specific address, with the engineering handled inside the scope.