buying a kit
LEGO has 2 main kits that are perfect if you are trying to learn robotics.
(1) The first is the LEGO Education WeDo 2.0. This kit is the much simpler of the two and perfect for younger children (ages 7-8) with little to no experience in engineering. The set has your typical LEGO pieces, a motor, a motion sensor, a tilt sensor, and the smart hub. Cost: around $200.
(2) The second kit is the LEGO Mindstorms EV3. Recommended for ages 10+, but if you really plan to stick with robotics, it's worth even if you are little younger. It comes with 2 large motors, 2 touch sensors, a gyro sensor, an ultrasonic sensor, a color sensor, and an expansive set of LEGO pieces. Yes, it is slightly harder, but provides much more flexibility for building and in the long run, will be much cheaper than purchasing the Wedo and then the EV3 after. No experience needed for this kit either - it comes down to price, age, and how far you want to go into learning LEGO robotics. Cost: around $400.
WeDo 2.0 is extremely simple and meant for children ages 7-8
LEGO Mindstorms EV3 is recommended for ages 10+
No prior experience is required for both kits