My DD is an only child and with not being able to see friends outside of school now her use of tech has significantly increased because she is bored of her own company (before lockdown she was happy to amuse herself tech free but never for months at a time) and there are only so many books to read and homework to do, especially after 7 months of exhausting all the usual options.
Before lockdown I used to limit DDs tech time by saying she could only have it once she had completed other tasks.
On school days she only watches TV before school if she has time left after getting up, making her bed, having breakfast, washed/teeth brushed, getting dressed and having everything ready to go by the door.
After school she has a snack, does her homework, sorts her things for the following day (bag packed by the door, any extra curricular supplies sorted and ready etc) and then if there is time before dinner she could have tech. After dinner we always watch TV anyway so she can choose TV or tech time until shower/reading/bedtime.
At weekends/holidays I usually employ a system where DD gets an hour of tech time as her "basic allowance" but she can only do it when she has completed a checklist of other stuff. Since lockdown I have tried to keep the same structure but the base allowance has been upped to account for the fact that there is no option for going out with friends/family currently.
Hers is - get up and make bed; make sure bedroom is tidy; have had breakfast; washed and dressed; homework finished, if she didnt complete it Friday night; an active activity at least planned for some point that day (so it used to be that she would arrange to walk to town or the park with some friends later that day or go swimming with her cousins but now it's more that we might go for a walk together or she does a YT video, maybe a kids yoga or dance tutorial video) and two chores from the chore jar ( I have a jar with cards with various household jobs that are age appropriate for DD, she chooses two of them to complete that day)
If she wants more tech time beyond that hour then there are opportunities for her to earn extra time - doing extra chores, helping with big home projects, doing something I want to encourage (eg theres a list of classic books she is working through, every time she completes one she earns extra tech time) - so she knows she will always have tech time but how much is directly correlated to her actions.