Existe sim.
No seu config.lua troque
experienceStages = "no"
por
experienceStages = "yes"
Agora vai na pasta do seu otserv/data/XML e abra o arquivo stages.xml
vai estar mais ou menos assim
<?xml version="1.0" encoding="UTF-8"?>
<stages>
<world id="0" multiplier="1">
<stage minlevel="1" maxlevel="40" multiplier="90"/>
<stage minlevel="41" maxlevel="90" multiplier="70"/>
<stage minlevel="91" maxlevel="120" multiplier="50"/>
<stage minlevel="121" maxlevel="140" multiplier="35"/>
<stage minlevel="141" maxlevel="160" multiplier="25"/>
<stage minlevel="161" maxlevel="200" multiplier="15"/>
<stage minlevel="201" maxlevel="250" multiplier="10"/>
<stage minlevel="251" maxlevel="350" multiplier="5"/>
<stage minlevel="351" multiplier="2"/>
</world>
</stages>
minlevel = Level minimo
maxlevel = máximo level
multiplier = a exp