Depends. 1st you need to find out if your phone/manufacturer allows unlocking the bootloader. No unlocking, no custom rom, no lineage os. If it is supported, you need to find a lineageOS rom for your phone. There is an official lineageOS website where you can find compatible devices. If it’s not listed there (which is not unlikely), you can search the web for unofficial lineageOS roms or other custom roms. Be careful, some of your phone’s features might not work properly or at all but most custom rom developers provide you with a list of what is and isn’t working.
And for the installation part, it’s probably better to look up a full tutorial on the web as installing a custom recovery that you need to install the rom can be a bit tricky…
Depends. 1st you need to find out if your phone/manufacturer allows unlocking the bootloader. No unlocking, no custom rom, no lineage os. If it is supported, you need to find a lineageOS rom for your phone. There is an official lineageOS website where you can find compatible devices. If it’s not listed there (which is not unlikely), you can search the web for unofficial lineageOS roms or other custom roms. Be careful, some of your phone’s features might not work properly or at all but most custom rom developers provide you with a list of what is and isn’t working.
And for the installation part, it’s probably better to look up a full tutorial on the web as installing a custom recovery that you need to install the rom can be a bit tricky…