When buying a lens you should consider the weight of the lens. A lens must be nice and confortable to hold and if it is heavy the weight can become a burden if your photo sessions are longer. The weight often seems like nothing when you first lift the lens but imagine holding it for hours and hours.
Here at Lensora you can see what each lens weighs and you can even see what the total weight becomes, where the weight of the camera and the lens are combined.
Larger telephoto lenses are often not meant for holding by hand and are instead equipped with a tripod mount, which gives you the opportunity to easily attach for example a monopod or tripod directly to the lens and by doing so have a greater stability when shooting. Nature photographers are often seen using the tripods while sports photographers usually use monopod.