1. Create a New TYPO3 Project

composer create-project "typo3/cms-base-distribution:^10.4" yamuna
cd yamuna

2. Install Your Required Extensions. Example:

composer require "typo3/cms-about:^10.4" "typo3/cms-adminpanel:^10.4" "typo3/cms-backend:^10.4" "typo3/cms-belog:^10.4" "typo3/cms-beuser:^10.4" "typo3/cms-core:^10.4" "typo3/cms-dashboard:^10.4" "typo3/cms-extbase:^10.4" "typo3/cms-extensionmanager:^10.4" "typo3/cms-felogin:^10.4" "typo3/cms-filelist:^10.4" "typo3/cms-filemetadata:^10.4" "typo3/cms-fluid:^10.4" "typo3/cms-fluid-styled-content:^10.4" "typo3/cms-form:^10.4" "typo3/cms-frontend:^10.4" "typo3/cms-impexp:^10.4" "typo3/cms-info:^10.4" "typo3/cms-install:^10.4" "typo3/cms-lowlevel:^10.4" "typo3/cms-opendocs:^10.4" "typo3/cms-recordlist:^10.4" "typo3/cms-recycler:^10.4" "typo3/cms-redirects:^10.4" "typo3/cms-reports:^10.4" "typo3/cms-rte-ckeditor:^10.4" "typo3/cms-scheduler:^10.4" "typo3/cms-seo:^10.4" "typo3/cms-setup:^10.4" "typo3/cms-tstemplate:^10.4" "typo3/cms-workspaces:^10.4"

3. Add Local Repository ./extensions/ Folder

composer config repositories.local '{ "type": "path", "url": "extensions/*", "options": { "symlink": true } }'

4. Install Your Local Extensions situated at ./extensions/ Folder

Clone all the extensions in the ./extensions/ folder and then include them one by one.

Note: Make sure that the composer.json file has version number in it.

composer req pdahal/bosstemplate
composer req ftn/projectmgmt

5. Copy the contents of typo3conf/sites folder to config/sites folder.

6. Copy typo3conf/AdditionalConfiguration.php and typo3conf/LocalConfiguration.php files to public/typo3conf/ folder

7. Copy fileadmin (and other folders) to public/ folder

That is it.