All is stock with the latest updated stuff, you can use the built-in configurator html page (kinda like OC suite online configurator) in a PC or use the wizard to able to configure it on-the-fly from switch overlay and just reboot to apply.
EOS is one thing and Lineon Conf5 is a different one... EOS is the updated OC suite and the Conf5 was specially made for erista by Lineon and allows very low CPU voltage at high clocks with no performance loss, EOS sadly still doesn't have that yet for Erista...
You can try "sys_clk..." + "EPV+Wizard" (which is Lineon Conf5 loader.kip but with the overlay to be able to configure from switch without needing Conf5 PC configurator.
If it doesn't work sadly you will have to use EOS instead or just use atmosphere 1.6.2 instead for now...
Also on my Erista I'm currently using GPU UV table which allows to chose voltage per each GPU frequency but I still haven't finished the whole setup on mine.
I'm currently using:
998mhz = 920mv;
921mhz = 885mv;
844mhz = 855mv;
768mhz = 820mv;
691mhz = 790mv;
Still need to find the lowest frequencies but that's the lowest I could go before having issues or lower performance on mine and somehow I'm getting even higher FPS with GPU UV compared to stock which doesn't make much sense on frequencies that I'm not both power or temp limited
Ram I'm currently using 2131mhz at EMC DVB 875mv with timings auto_adj_all (4-2-5-5-3-5-2) but at high voltage of 1.3125v...
I recommend using ram set to No_adj_all and set max voltage of 1.175 and go for the highest frequency you can get at that voltage which is the max "factory spec" safe voltage for the ram chips, some lucky Eristas can actually do 2131mhz at that voltage but most will need like 1.25v or more specially when using gpu_uv seems to require more voltage to be stable.
Ps: in my opinion it's totally fine going above 1.175v on the ram and almost everyone achieving the highest will always use a lot more, but I recommend at least some cooling on the mems and mems are one of the things that usually bring the highest FPS as switch is severely mem bandwidth capped on most games and by far what brings highest performance per lowest power consumption, I measured around 0.6w more from stock mem voltage at 1600mhz to mine at 2131mhz higher voltage which higher CPU\GPU clocks it jumps quickly pretty high.
4IFIR mod 4 example uses crazy 1.35v for 2133mhz on Erista which I totally don't recommend...
EDIT: Attached is an example of the wizard that allows you to configure your loader.kip from switch overlay (this is the conf5 wizard "EPV + Wizard" but the EOS toolkit one should be similar...)
EDIT2: Added testing apps and a nice overlay to test in-game performance on my previous post, removed the picture and put the ".rar" files.