New toilet already clogging?
A lot depends on how severe a clog you have:


An extra flush gets it going


You may have a toilet that isn't well designed. A lot of earlier low-water-usage toilets had this problem. But there may be adjustments you can make to the flush mechanism inside the tank to increase the amount of water used for each flush.


Plunger needed, but nothing more


In this case, it is likely a clog "nearby" - e.g., perhaps something clogged the pipes during renovation and has narrowed the pipe a bit. And it could also be a vent problem (though I admit I really don't understand vents myself). But it would not be something "far away" as that would likely affect other fixtures too.


Snake required


If you need a snake to fix the clog then this is much more serious. Could be a vent problem (as I don't totally understand plumbing vents, I can't say more than that) or it could be a drain pipe problem farther down that is "catching" some waste from the toilet when it shouldn't.