How to merge Outlook 2016 .pst file with/into newly created Outlook 2024 installed .pst file?

Question is above.

Would it be best to "Export" the .pst file from within the Outlook 2016 app, then "Import" the .pst file into the new Outlook 2024 app?
Or just "Copy" the Outlook 2016 .pst file from its File folder and "Paste" it onto the new Outlook 2024 .pst file in its new File folder?

Also, can I Change the new Outlook 2024 .pst Folder Name and Location without messing up the app?

Try File -- Open and Export --> Import and Export --> Import from another program or file.

How about changing the New .pst Folder Name and Location?

You do not "merge" the pst files.
1. On newly created account click file>account settings>manage profile.>data files
That tells you where its data file is stored. Go to that location and copy that new pst file to some other location temporarily.

2. Delete the new pst file. Then copy your old pst in its place. Close & reopen outlook and see if the newly created email account will open using that old pst file

If for some reason it won't , you can put the .pst you copied in step 1 back in.

How about this.

1. Use Outlook settings Open and Export to Import the new PST file
2. Once you have that new PST file open in Outlook, then drag and drop folders from the new PST file to the existing PST file. Outlook will deal with folders of the same name in both PST files.
3. When you are finished, CLOSE that new, now empty PST file
4. Close Outlook
5. Delete the now empty new PST file.