I changed the brake pads on a Hilux and after doing so, the pedal has gone very spongy. The brake fluid also seems to have risen above max. When I start the car, the first press of the brake pedal seems normal but after that it’s very spongy.
Do a preliminary check of the hydraulics and vacuum booster by holding down the brake pedal and feel if there is continuous release of pressure. Pulse the brake pedal repeatedly and continue pulsing while your turn off the engine. The pedal should get harder and harder to push and eventually settle to a consistent pressure on your foot with no 'lag' and additional slow downward movement.
If the 'sponginess' is only when you are trying to stop the moving car you may have oil or contaminants on the rotors or may need to break in the pads.
Best to refresh the system by doing a hydraulic bleed if possible. As a stopgap measure keep a continuous check on the fluid reservoir and keep a periodic visual leak check on each caliper piston and hoses.
Again you may just have oil on the rotor.
If you did only change the brake pads and pushed the caliper pistons back the brake fluid level will go up.
You should not need to bleed the calipers after this,it is not unusual that the brake pedal feels a little spongy after changing brake pads but it should get back to normal in a short time after some driving.
If the pedal still feels spongy after a week of normal use of your car you need to have it looked at.