Use acpi instructions from here:

https://wiki.archlinux.org/index.php/Lenovo_IdeaPad_5_14are05#Suspend_issues_(S3_sleep_fix)

Failed to recompile for me, had to go in and edit line:

Update: I was able to solve the compile issue by changing line 29 in my dsdt.dsl file:
CODE: SELECT ALL

External (_SB_.PCI0.GP17.VGA_.AFN7, UnknownObj)
to the following:
CODE: SELECT ALL

External (_SB_.PCI0.GP17.VGA_.AFN7, MethodObj)

as per: https://forums.linuxmint.com/viewtopic.php?t=332195

Then once you've recompiled do:

mkdir -p kernel/firmware/acpi
cp dsdt.aml kernel/firmware/acpi
find kernel | cpio -H newc --create > acpi_override

The following the instructions here:

https://wiki.archlinux.org/index.php/DSDT

Add your acpi_override file to kernel parameters as initrd line in /boot/loader/enteries/arch.conf 

reboot and check:

dmesg | grep ACPI | grep supports

[    0.195933] ACPI: (supports S0 S3 S4 S5)

(S3 is the mode you want) After that suspend worked for me.