Depends on how the partitions are arranged. I'm assuming your Windows is first (going left to right), then probably your boot partition, then your main ext4, and then maybe a swap?
Definitely shrink the windows partition using disk management, but then in Linux you can clone your boot partition to the beginning of the free space, delete the old boot, and then expand the ext4. You don't HAVE to do it from a live environment, but it is the safest.
I didn't google much, but this seems about right: https://www.baeldung.com/linux/resize-partitions
ionos.com is $1/month and you can use external domain names. That plan includes the cost of a domain name as well, so you can transfer the external domain over if you really like it.