Recommendations from RH 8 and CentOS and Fedora 29

Amount of RAM in the system
Recommended swap space | Recommended swap space if allowing for hibernation

Less than 2 GB
2 times the amount of RAM | 3 times the amount of RAM

2 GB - 8 GB
Equal to the amount of RAM | 2 times the amount of RAM

8 GB - 64 GB
4 GB to 0.5 times the amount of RAM | 1.5 times the amount of RAM

More than 64 GB Workload dependent
(at least 4GB) | Hibernation not recommended

CentOS adds: the installer won't use more than 10% of the system's
storage space.

Generally, CentOS recommends a storage space of at least 1G.

Also they recommend at least:
200M for the ESP
1M for the Bios Boot partition
55G total for a /home partition to be created

CentOS notes:
Neither the biosboot nor efi partition can reside on an LVM volume. Use
standard physical partitions for them.

Placing the /boot partition on an LVM volume is not supported.

By default, the installation process always creates the / and swap
partitions within LVM volumes, with a separate /boot partition on a
physical volume.
You can lose data if you shrink a logical volume to a smaller capacity
than the data on the volume requires. To ensure maximum flexibility,
create logical volumes to meet your current needs, and leave excess
storage capacity unallocated. You can safely extend logical volumes to
use unallocated space, depending on your needs.

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/logical_volume_manager_administration/lv

For Ubuntu settings:
https://itsfoss.com/swap-size/

Quote of the latter:There are several reasons why you would need swap.
> If your system has RAM less than 1 GB, you must use swap as most applications would exhaust the RAM soon.
> If your system uses resource heavy applications like video editors, it would be a good idea to use some swap space as your RAM may be exhausted here.
> If you use hibernation, then you must add swap because the content of the RAM will be written to the swap partition. This also means that the swap size should be at least the size of RAM.
> Avoid strange events like a program going nuts and eating RAM.

> If RAM is less than 1 GB, swap size should be at least the size of RAM and at most double the size of RAM
> If RAM is more than 1 GB, swap size should be at least equal to the square root of the RAM size and at most double the size of RAM
> If hibernation is used, swap size should be equal to size of RAM plus the square root of the RAM size


Deending of RAM size:
No more than 4G: /2G or 1G
More than 4G: 20% de la RAM but no more than 10% of teh space on disk.
(more for hibernation)

To display the RAM size:
LANG=C vmstat -s|grep "total memory"
cat /proc/meminfo |grep MemTotal
free -m | awk '/Mem\:/ { print $2 }'