Update & Tune-up & Housekeeping for Joomla 3.10.5 site and migrate to Joomla 4

Hello Joomla freelancer, I am looking for a Joomla expert who can take a look and fix any problems and make any improvements to keep the site working well. I have let it go for a while now and there are a few issues to sort out.
If possible, I would also like to migrate the existing site to the latest Joomla 4. version and update the PHP version.
In addition, there are a lot of unnecessary files and folders and extensions and data bases and other junk in the site admin and in the control panel files. I would like to have ALL non-essential items archived, removed or deleted, keeping only what is need to keep the site functioning correctly.
I also have been working on new logos and a new color pallet and that could also be updated at this time.
Installing a new booking extension or other useful extensions can also be considered.
I am also happy to hear any other recommendations for improvements.
The budget can be adjusted, depending on what work we can agree on, but reasonable, affordable costs are essential.
SailQuest Sailing School Thailand website: www.sailingschoolasia.com
Please take a look and if you are interested and are able to make a positive effort, I am looking forward to hearing from you and viewing your proposal.

Thank you,
Capt. Tim