Zurich on Easter Sunday
In Switzerland most commercial locations are closed on Sundays anyway. But those establishments that are open on Sundays will mostly also be open on Easter Sunday, it is not a legal holiday.
A quick look at these:
Kunsthaus (art museum) open 10-6
Rietberg Museum (art museum) open 10-5
Swiss National Museum "Landesmuseum Zürich" open 10-5
Zoo open 9-5
But aside from museums it will be worth your while to go into town - it's a short ride on a train that leaves from underneath the airport terminal building - the one adjacent to the arrival halls.
Simply buy a ticket to Zürich HB from an automat - "retour" means there-and-back. Look at the signage above the stairs that lead down to the tracks, and go board the next train headed for Zürich HB. It may be a nonstop, or it may make a quick one-minute stop in Oerlikon - same difference.
Announcements are made in German and French and English, coming back you'll be getting off at "Flughafen-Aéroport-Airport".
From the main train station (Zürich HB = Hauptbahnhof) either cross over to the National Museum just to the north of the station (on "Museumstrasse"), or go for a stroll through the old town:
Cross the river (Bahnhofbrücke - "train-station bridge") and turn right (south), either along the river (Limmatquai) or along the Niederdorfstrasse one street over from the river. Just amble around, and take the fourth opportunity to cross the river again. The bridge is called "Münsterbrücke" (cathedral bridge), and you're looking at the Fraumünster cathedral. If there is no religious service in progress, see if you can go in to see the Chagall windows.
Then keep going, in a minute you'll be by the lakefront where you can hop on a boat and enjoy the scenery up and down the river Limmat - see https://www.zsg.ch/en/limmat-river-cruises.html - or on the lake - see https://www.zsg.ch/en/. On a good day you can see the distant alps. The boats start running on Aprl 2nd so you should be in luck.
If you want to experience sticker shock without being in danger of going broke, go window-shopping along the Bahnhofstrasse. Most of it is traffic-free. Since shops will be closed, you and your credit cards will be safe...
Another nice thing to do would be - on a good clear day - to go up on the "mountain" of Zürich, the Uetliberg. Lunch up there would be nice, but on Easter Sunday there might not be a table free... Anyway see www.uetliberg.ch/en
Realize that April is the proverbial month of changeable weather, minute by minute.