Really a question with so many variables- it’s impossible to answer.
What if I changed “mineral rights” to “pre- existing structure” / would you buy land with a structure on it? Would you pay more for it?
The answer of course depends on buyer, the land and the structure as well as the structure. If the structure was an old barn or shed...you may pay a little more or nothing at all...if it’s a fully furnished modern home - you’d likely pay more but someone seeking bare land for grazing likely would not have any interest. If it was an abandoned factory - you’d probably pay less as the cost of clean up cost adds quickly.
Ditto minerals...do minerals add value - sometimes...a lot...occasionally. Oil & Gas rights can be a few hundred an acre to 20k+ in select areas with a producing well. Coal is basically an afterthought these days.
Buying without - need to see the mineral deed to see what has been granted and know the state..some states are very generous to mineral owners rights...others give the surface owner much more power.