LinuxQuestions.org - ibdata1 too large and enlarging root partition in Centos 7

I have an issue on my Centos 7 system, and I will be trying to find the best way to go after coming back from a break. I've been already working on it for 6+ so far.

I have a root partition of 20G in size and it is running out of space because the /var/lib/mysql/ibdata1 is getting too large (13G now, the whole /var/lib is 15G in size).

lsblk command shows something like this:

sda
-sda1
-sda2 (mountpoint /)
-sda3
--volgroup1-lvol0 (mountpoint /home)
-sda4 ([swap])
sdb
-volgroup1-lvol0 (mountpoint /home)

So basically the sda2 is the / partition with the 20G of space and sda3 + sdb is /home partition with space of 3.6T created with LVM.

1) Is it possible to enlarge the / partition (to lets say 100G or maybe more would be needed) and what would be the best way of doing that.

2) Is there any way of mitigating the problem of the /var/lib/mysql/ibdata1 getting too large?

I still have a lot of space on the /home partition and I can easily expand the / partition from the 20G to 200G if this would be a good thing to do. I will be still able to work on what I am working on with something like this.

I would like to solve this as good as I can, and dont have any problems related to this when I work on my site on this hosing plan.

Thanks.

Edit:
/dev/sda2 and /dev/mapper/volgroup1-lvol0 are both ext4, I run df -T to get the info about that.

Edit2:
This is on a working system, so I would need to do it while everything works. I am not able to disable the websites for some time on order to work on this. Is this all a doable thing?