https://en.wikipedia.org/wiki/Presidential_state_car_(United_States)

The 2009 presidential state car model had night vision optics, a tear gas cannon, onboard oxygen tanks, an armored fuel tank filled with foam to prevent explosion, and pump-action shotguns.[1][26] Whether it was[29] or was not armed with rocket-propelled grenades,[26] the car featured eight-inch (200 mm) doors.[10]

In addition to defensive measures designed to protect the president, this state car has stores of blood in the president’s type for medical emergencies. The car is hermetically sealed against chemical attacks, and features run-flat tires, night-vision devices, smoke screens, and oil slicks as defensive measures against attackers. NBC reported that the car features armor made of aluminum, ceramic, and steel; the exterior walls have a thickness of eight inches (200 mm), the windows are multi-layered and five inches (130 mm) thick, and each door[32]—believed to be one foot (0.30 m) thick[37] and weigh as much as those on a Boeing 757—can electrify its handles to deter entry.[32]

https://spyscape.com/article/7-top-secrets-about-the-beast-presidential-limo

There are at least two identical Beasts with matching registration plates in every motorcade so attackers can’t be 100% certain which vehicle contains the president and which is the decoy. During President Joe Biden’s inauguration, there were actually seven Beasts deployed in the mother of all motorcades.

https://en.wikipedia.org/wiki/Secret_Service_Counter_Assault_Team

“Hawkeye” is the designation for a CAT assigned to the president, followed by the president’s Secret Service code name

CAT operates both as part of motorcades and at fixed sites. In the event a VIP, the VIP’s vehicle, or a protected site is attacked by multiple assailants, CAT is responsible for engaging and diverting the attackers, thereby buying the close protection shift time to evacuate the dignitary to a safe area.[9]

Hawkeye, when operating as part of a U.S. president’s motorcade, travels in a vehicle several car lengths behind the presidential state car.[11]

A pop-up Gatling gun that comes out of a roof turret on one of the support vehicles:

https://www.guns.com/news/2011/07/16/the-dillon-m134d-gatling-gun-the-secret-services-secret-weapon

The Dillon M134D Gatling Gun: The Presidential Motorcade’s Secret Weapon

No doubt other stuff that isn’t made public.

They have closed airspace around him and they have fighter jets that will come investigate aircraft getting close.

https://www.faa.gov/newsroom/restricted-airspace-0

In the case of Presidential movement, the TFR is usually comprised of an outer ring (usually 30 nautical miles, but sometimes slightly more or less) and one or more inner rings (usually 10 nautical miles, but sometimes 8, 9, or 10 nautical miles). The dimensions and, even the shape, of the rings are sometimes altered to suit specific needs. For example, some TFRs are structured so that the outer ring consists of the lateral limits of a particular airport’s Class B airspace, or are created with cut-outs, as noted later in this resource.

I wouldn’t be terribly surprised if, especially in this era of easy accessibility to drones, if they’re also carrying some sort of surface-to-air weaponry, though I don’t think I’ve ever read anything about it. They have electronic warfare vehicles in the convoy, though as can be seen in Ukraine, where Russia and Ukraine are both using drones that unspool fiber optic cable behind them as they fly to defeat jamming, jamming is not, alone, a full counter to drones.