In the vmxnet3s.conf you can apply settings for 1..10 vnics in a commalist.
my default setup is like
TxRingSize=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
RxRingSize=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
RxBufPoolLimit=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
EnableLSO=0,0,0,0,0,0,0,0,0,0;
MTU=1500,1500,1500,1500,1500,1500,1500,1500,1500,1500;
my default setup is like
TxRingSize=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
RxRingSize=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
RxBufPoolLimit=4096,4096,4096,4096,4096,4096,4096,4096,4096,4096;
EnableLSO=0,0,0,0,0,0,0,0,0,0;
MTU=1500,1500,1500,1500,1500,1500,1500,1500,1500,1500;