SQL Server Service and Analysis Service Issues

Hi, please forgive me if this is not posted in the correct forum, any signposting would be appreciated.

I was hoping to get some help and insight into how I might be able to inspect what's happening with one of our Business Intelligence servers that has SQL Server installed.

Long story short (and I don't know what information will be pertinent) we have a WIndows 2016 server that is unable to cope and is affecting performance of two applications.  The Task Manager shows that CPU and Memory usage on this server is 90%+ for sustained periods, with a combination of the SQL Server Analysis Service, Reporting Services server and SQL Server Windows NT - 64 Bit consuming the CPU and Memory.

My question is how I might learn further about what activity is constituting the consumption of resources.  I have access to the Windows server, and limited database access, but I am unsure as to if there are any tools that would allow me to see what's happening to cause the high utilisation.  We have a DBA team that are constantly under pressure and although they are helpful, I wondered what I would need to be able to investigate the issue further myself.

I suspect that there's lots of information I'm leaving out here, but I'd be grateful for any pointers anyone may be able to give me.

Many thanks for looking.