Change the default "product page" font and alignment?

[Heroine]

as title

so i can’t really find anything that i can customize the layout of the “default product page” and also “contact” page

I would like to change the size and also the word"products" and change “contact” into " contact us" and move the "contact us aligment to the left instead of center

thanks

[Moeed]

Hey @Heroine
Kindly share your Store URL and Password if enabled

[Heroine]

I am totally a newbie here,may i know how?