Is there an estimate of the mass Artemis Landers must be able to deliver to the Lunar surface? I am interested in the total mass - vehicle and payload on arrival - as well as a breakdown of how much mass is delivered for on moon use and how much is required to support launch back to space?
This depends heavily on the lander.
For example, Peregrine Mission One with the Peregrine lander from Astrobotics will carry 28 payloads with a total mass of up to 256 kg. The lander itself has a mass of 1283 kg. Peregrine has no upmass capability, it is a pure, expendable, lander.
IM-3 with the Nova-C lander by Intuitive Machines will land 92 kg.
The VIPER rover will be landed by a Griffin lander, also by Astrobotics. Griffin's mass is 450 kg, VIPER's is 430 kg.
For the CLPS program alone, NASA has awarded contracts to 5 companies with 6 different landers. Each lander has different mass and different payload capabilities. It is impossible to give a general answer.
As far as I can see, none of the CLPS landers has any way of taking off again, so at least this part of your question can be answered in general:
how much is required to support launch back to space?
Nothing. None of the CLPS landers have this capability, but NASA selected them anyway, so clearly, this is not a requirement for CLPS.
This is different for other programs, of course. HLS, which is also part of Artemis, requires upmass capabilities, for obvious reasons: you don't want your astronauts stuck on the Moon forever.