Typically they touch down lightly (staying on the step of the seaplane hull), extending pickup probe(s) and increasing power to compensate for drag of probe.
Retract probe and increase power as needed (the probe(s) create a lot of drag).
BTW, the CL415 is amphibious whereas the Mars is strictly a seaplane. Shin Maywa US-2 is amphibious, now comes in a fire tanker version of about 3300 USG capacity so twice the CL415.
(Adding to the fleet now fighting LA fires, a couple of US military Hercs with the spurt-out-paradrop door system, much less capacity than Coulson’s RADS tank system which former USCG Hercs will have for next year.)