Hello to everyone

I have a Dell Inspiron 15 3521 i5-3337U 1.80 GHz 4 gb RAM.
I bought this computer in 2013. I want to upgrade RAM and SSD because it seems slow to me now.
There are articles in the community on this subject, but I want to ask for sure, sorry for that. (Sorry for my English too, I use google translate.)

According to the information I see, a maximum of 8gb ram can be used.
In the videos I saw here and on youtube, I saw them upgrade to 16 gb ram.

What kind of problems can this have? My computer has been out of warranty for years. Do you think I should upgrade 8 gb ram?
Or should I upgrade to 16gb ram?

I think Samsung 860 Evo Sata 3.0 Ssd Disk 500 gb as ssd. Do you think this would be compatible?

Thank you very much for your answers. Again, I apologize for my English, have a nice day.