First and foremost, "Mauser 98" doesn't really tell us the whole story as that's a somewhat generic term that can mean a lot of different things. Was this gun originally built as a military rifle or was it built from the ground up as a sporting rifle? Is it an actual German Mauser-built rifle or was it a "Mauser 98 pattern" rifle built under license in one of any number of countries (Czech VZ-24, Yugo M -48, etc.)? Was your rifle made during peace time or during the height of one of the two world wars or countless smaller ones? The Mauser 98 was the most prolific rifle design of the late 19th and early 20th century and was adopted, adapted, licensed, and copied by dozens, if not hundreds, of different countries for 50+ years with varying degrees of fit, finish, and quality.
Due to its design, the bolt handle of a Mauser 98 pattern rifle will be more difficult to lift when the striker is not cocked. This is because it is a "cock on opening" design and lifting the bolt handle cams the striker back into the cocked position. If the striker is already cocked, the bolt handle will be easier to lift because you don't have to compress the striker spring as you do when the striker is in the fired position. Also, in my experience, Mausers and other cock-on-opening military rifles such as Mosin-Nagants and Carcanos often have stiffer bolts than commercial cock-on-opening rifles like a Winchester Model 70 or Remington 700. This is likely due to the fact that the camming surfaces in military rifles often aren't as smoothly polished as those of commercial rifles and military rifles often have stiffer striker springs to ensure reliability with military ammunition that often has harder primers.
That being said, the bolt of a Mauser 98 in good working order should not be so stiff that it is difficult for an adult of average strength to manipulate it. If the bolt is excessively difficult to open, this could be a sign of problems like excessive headspace, dried oil, grease, or other debris in the locking recesses and/or chamber, or dried oil/grease/debris inside the bolt itself. If the bolt of your rifle is excessively stiff or difficult to manipulate and the serial number of the bolt (if it has one) matches the rest of the rifle, I would start by giving the entire rifle but particularly the bolt and chamber a thorough cleaning. If the problem persists after that, you should probably take the rifle to a competent gunsmith to have it checked for headspace and other issues.
