Zend certified PHP/Magento developer

Nesting Pruduct details default block in my custom block

I would really appreciate a hand here – thanks in advance for any tip, I’m fairly new to Magento’s layout structre.

I’ve created a custom block via backend. In that block, among other things, I would like to include the default Product details tabs from Product Page [my block has 3 vertical bootstrap clomuns, I would like the item’s description to go into the first one, the default generated attribute list tab into the middle one and in the third I have my own child-block I’ve created’.
How can I accoplish that? I looked for a tag or block number for the default blocks, but that didn’t get me anywhere. [I thought I could copy the structore of the third block and just switch the block’s ID, but sadly got nothing out of it].

I know I somehow need to make those default tabs into child-blocks but not sure how. Maybe the fact that I’m using a theme matters?

Magento 2.3.3, theme: Pearl by WeltPixel, Product Page info set to ‘List’ [not Tabs/Accordions – but I can change that if needed].
Thank you in advance for any tips you might have for the rookie! I would so much appreciate those! [And please, when reffering to a file structure, include the folder after the root, so I could be sure I’m doing exactly what I should be doing – still quite new to digging into this. Thanks!]