If you are using Gutenberg and a block theme you can do it with group and cover blocks.
To do it:
Add a group block and set to full width. In the dimensions, set the block spacing and the margin to 0.
Add a cover block inside that. Set to full width with the background image set to fixed. Add any content blocks to it you want.
Repeat for each section. You can copy/paste the original Group containing the first one then edit that copy with new content.
[Example]) First two sections just Grouped Cover blocks with a text block inside. Third section is a Grouped Cover block with a Text/Image block pattern added.
For the dot menu, you could create a sticky navigation similar. Use anchor links to each section.
If you are using Gutenberg and a block theme you can do it with group and cover blocks.
To do it:
Add a group block and set to full width. In the dimensions, set the block spacing and the margin to 0.
Add a cover block inside that. Set to full width with the background image set to fixed. Add any content blocks to it you want.
Repeat for each section. You can copy/paste the original Group containing the first one then edit that copy with new content.
[Example]) First two sections just Grouped Cover blocks with a text block inside. Third section is a Grouped Cover block with a Text/Image block pattern added.
For the dot menu, you could create a sticky navigation similar. Use anchor links to each section.