@Hari My responses below
change PHP version to 8 at the server level and also for my domain in Plesk using SSH
PHP 8.x has been available in Plesk since October 2021. There’s no need to change this using SSH, and it’s actually not recommended. The entire point of Plesk is to manage this using the portal - see below
https://support.plesk.com/hc/en-us/articles/115000769793
instead of maria DB i want to use MySQL as default, how can i do that? is it really possible? without a docker or any other things (since i am getting those SQL errors as shown in the earlier reply want to switch to MySQL from MariaDB)
Possible, yes - although it’s usually the other way round in the sense that people want to replace MySQL with MariaDB
https://www.plesk.com/blog/product-technology/mysql-vs-mariadb/
update composer to v2 for my domain via SSH.
You should take the same route as is advertised here
https://getcomposer.org/download/