You need to add extra backports sources tou your sources list:

echo "deb http://deb.devuan.org/merged <my_dist>-backports main contrib non-free" >> /etc/apt/sources.list

according to your OS change <my_dist> with ascii or beowulf

apt update

To know how kernel are installed:

uname -a

To search a newest kernel:

apt search linux-image

In the output we will see a lot of kernels, but we have interest to the latest, at this time the kernel 5.7:

Lets do it and install the latest kernel:

apt install linux-image-5.7.0-0.bpo.2-amd64 linux-headers-5.7.0-0.bpo.2-amd64 -t buster-backports -y

A reboot is needed to boot on the new kernel:

reboot

We can check now:

uname -a

The output:

Linux my-pc 5.7.0-0.bpo.2-amd64 #1 SMP Debian 5.7.10-1~bpo10+1 (2020-07-30) x86_64 GNU/Linux

let's take it a step further by removing the old kernels, in general it is advisable to keep 2 kernels in case there is a problem with one of them.

To view the installed kernel:

dpkg --list 'linux-image*'

In the output you will see how kernel you can purge, in my case i keep the 4.19 and the 5.7 and purge the 5.6.

Example to purge a kernel:

apt autoremove --purge linux-image-5.6.0-0.bpo.2-amd64 linux-headers-5.6.0-0.bpo.2-amd64 -y

We need to upgrade the grub with the changes we made:

update-grub2

After an reboot in the boot menu, select advanced options, you can also check the kernels who are usable.

In case if you have a graphic card using open firmwares you'll need to update your kernel with it, just check this tutorial